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Biomedical subjects

D Nelson

Publications and source records attributed to D Nelson.

At least 163 records · Page 9Linked to original sources
PubMed1994

Gene organization of the pregnancy-specific glycoprotein region on human chromosome 19: assembly and analysis of a 700-kb cosmid contig spanning the region.

The pregnancy-specific glycoprotein (PSG) gene family consists of 11 closely related genes that form a subgroup of the carcinoembryonic antigen (CEA) gene family on 19q13.2. Using a high-resolution restriction fragment fingerprinting technique, we have assembled 256 cosmids from the PSG region into a single 700-kb contig. Fluorescence in situ hybridization to sperm pronuclei and cosmid walking experiments indicated that this PSG contig was directly telomeric of CGM8 at the telomeric end of the CEA subgroup gene cluster. Detailed restriction mapping and hybridization with gene-specific probes indicated that the order of the 11 Previously identified PSG genes is cen-PSG3-PSG8-PSG12-PSG1-PSG6-PSG7-+ ++PSG13-PSG2-PSG5-PSG4-PSG11-tel. The CEA subgroup gene CGM11 is located at the telomeric end of the PSG gene cluster. The PSG genes are all oriented in tandem with the 5'-3' direction of transcription from telomere to centromere. The detailed map also led to the identification of seven new CEA family genes in this region. One of these (CGM12), located between CGM8 and PSG3, is a member of the CEA subgroup. The remaining six (CGM13 through CGM18) are interspersed among the PSG genes and appear to form a third distinct subgroup within the CEA gene family.

Animals↗
PubMed1994

Isolation and characterization of a mouse amelogenin expressed in Escherichia coli.

A mouse cDNA encoding a 180 amino acid amelogenin was subcloned into the pET expression plasmid (Novagen, Madison, WI) for production in Escherichia coli. A simple growth and purification protocol yields 20-50 mg of 95-99% pure recombinant amelogenin from a 4.5-liter culture. This is the first heterologous expression of an enamel protein. The expressed protein was characterized by partial Edman sequencing, amino acid composition analysis, SDS-PAGE, Western blotting, laser desorption mass spectrometry, and hydroxyapatite binding. The recombinant amelogenin is 179 amino acids in length, has a molecular weight of 20,162 daltons, and hydroxyapatite binding properties similar to the porcine 173 residue amelogenin. Solubility analyses showed that the bacterially expressed protein is only sparingly soluble in the pH range of 6.4-8.0 or in solutions 20% saturated with ammonium sulfate. The purified protein was used to generate rabbit polyclonal anti-amelogenin antibodies which show specific reaction to amelogenins in both Western blot analyses of enamel extracts and in immunostaining of developing mouse molars.

Amelogenin↗
PubMed1994

The use of a curriculum model in an Accident and Emergency Department.

This paper describes the adaptation and use of Beattie's curriculum model in an Accident and Emergency (A/E) Department. The rationale behind the undertaking was to reduce the incongruity between the triangle of the college, A/E and the student that creates the theory-practice gap in the context of A/E nursing. The article discusses firstly the decision to use a curriculum model. Secondly the reasons for the choice of model and the factors influencing that choice are discussed. The difficulties in applying the model and teaching methods that may be employed are examined. Student evaluation and the difficulties encountered in implementing the model is the final avenue explored. The article concludes that the strength of Beattie's model in A/E lie in its eclecticism. By combining all four approaches, the practical and theoretical contexts become integrated and in doing so reduce the theory/practice gap between A/E, the college and the student. It also provides a sense of balance for both student and teacher alike, amalgamating the four design briefs with the differing teaching methods thus catering for both group and individual student's differing learning styles.

Clinical Competence↗
PubMed1994

Abscisic acid promotes novel DNA-binding activity to a desiccation-related promoter of Craterostigma plantagineum.

Abscisic acid-treated callus of the resurrection plant Craterostigma plantagineum tolerates extreme desiccation. Nuclear proteins from tolerant callus bind specific sequence elements in the promoter region of the ABA and desiccation-inducible CDeT27-45 gene. One specific region of the promoter, which is protected from DNAase I treatment by DNA-binding activities, is different from previously reported ABA response elements. Four complexes of nuclear proteins and this DNA region are detected by electrophoretic mobility shift assay: two of these complexes (I and II) are readily detectable in untreated samples and are increased by ABA treatment while two other complexes (III and IV) accumulate only following ABA treatment and are prevented from accumulating by protein synthesis inhibitors. When a fragment containing the novel binding site is deleted from the wild-type promoter the ABA responsiveness of the promoter is removed; however, gain of function experiments using synthetic promoters in a protoplast transient assay suggest that besides the binding site other promoter elements are required. A second region of the promoter, containing the sequence element ACGT which is found in abscisic acid response elements, is also bound by nuclear proteins. The level of this second binding activity is similar in both untreated and ABA- treated cells and promoter/reporter gene constructs which contain only the four ACGT elements of the CDeT27-45 promoter are not ABA responsive in a C. plantagineum transient assay system.

Abscisic Acid↗
PubMed1994

Cerebral alanine transport and alanine aminotransferase reaction: alanine as a source of neuronal glutamate.

Alanine transport and the role of alanine amino-transferase in the synthesis and consumption of glutamate were investigated in the preparation of rat brain synaptosomes. Alanine was accumulated rapidly via both the high- and low-affinity uptake systems. The high-affinity transport was dependent on the sodium concentration gradient and membrane electrical potential, which suggests a cotransport with Na+. Rapid accumulation of the Na(+)-alanine complex by synaptosomes stimulated activity of the Na+/K+ pump and increased energy utilization; this, in turn, activated the ATP-producing pathways, glycolysis and oxidative phosphorylation. Accumulation of Na+ also caused a small depolarization of the plasma membrane, a rise in [Ca2+]i, and a release of glutamate. Intra-synaptosomal metabolism of alanine via alanine amino-transferase, as estimated from measurements of N fluxes from labeled precursors, was much slower than the rate of alanine uptake, even in the presence of added oxoacids. The velocity of [15N]alanine formation from [15N]glutamine was seven to eight times higher than the rate of [15N]-glutamate generation from [15N]alanine. It is concluded that (a) overloading of nerve endings with alanine could be deleterious to neuronal function because it increases release of glutamate; (b) the activity of synaptosomal alanine aminotransferase is much slower than that of glutaminase and hence unlikely to play a major role in maintaining [glutamate] during neuronal activity; and (c) alanine amino-transferase might serve as a source of glutamate during recovery from ischemia/hypoxia when the alanine concentration rises and that of glutamate falls.

Alanine↗
PubMed1994

Effects of 3-nitropropionic acid on synaptosomal energy and transmitter metabolism: relevance to neurodegenerative brain diseases.

3-Nitropropionic acid (3-NPA) inhibited synaptosomal respiration in a dose-dependent manner; the degree of inhibition by the same concentration of the compound was greater, however, when respiration was stimulated by concomitant increase in ATP usage. The most rapid event after addition of 3-NPA was a decrease in [creatine phosphate]/[creatine] ([CrP]/[Cr]) and an increase in [lactate]/[pyruvate]. A fall in [ATP]/[ADP] and [GTP]/[GDP] was initially less pronounced but closely followed that in [CrP]/[Cr]. In the absence of glutamine, 3-NPA caused a pronounced decrease in internal aspartate level and a small reduction in glutamate concentration, whereas [GABA] rose; the sum of these three amino acids inside synaptosomes fell, but there were no increases in their external levels. With glutamine in the medium, the reduction in intrasynaptosomal aspartate was accompanied by increases in intrasynaptosomal glutamate and GABA. The external concentration of glutamate rose substantially in the presence of the inhibitor. 3-NPA had no effect on basal release of either glutamate (and GABA) or biogenic amines but increased efflux occurring upon addition of nonsaturating concentrations of the depolarizing agents veratridine and KCl. The results allow the following predictions with respect to the behavior of brain metabolism in neurodegenerative diseases that involve restrictions of mitochondrial function: (1) The extent of inhibition of mitochondrial ATP generation is expected to be greater in cells with high energy demand. The earliest signs of impairment of the respiratory chain function are a fall in [PCr]/[Cr] (or a rise in [Pi]/[CrP]) and an increase in [lactate]/[pyruvate]. (2) A fall in [GTP]/[GDP] can limit protein synthesis.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphate↗
PubMed1994

A high-sensitivity immuno-chemiluminescence technique for detection of oligoclonal IgG and IgM in unconcentrated cerebrospinal fluid.

A method is described for detection of oligoclonal IgG and IgM in unconcentrated cerebrospinal fluid (CSF). The proteins were separated by agarose gel electrophoresis and transferred to cellulose nitrate membranes. A double antibody technique with a peroxidase conjugated secondary antibody was used to detect the protein. Bound secondary antibody was visualized by autoradiography using chemiluminescence (ECL) reagent. The procedure presented here allows examination of oligoclonal bands of IgG and IgM in less than 6h. The detection limit for a single band was approximately 10pg and the results were in complete agreement with those achieved by isoelectric focusing (Phast System) and subsequent immunofixation. In 9 of the samples oligoclonal IgM was also detected.

Electrophoresis, Agar Gel↗
PubMed1994

Diaspirin crosslinked hemoglobin (DCLHb): bioanalytical studies in swine.

These studies were a part of preclinical safety and efficacy studies of DCLHb. Their purpose was to analyze the characteristics of DCLHb during circulation, and the distribution of iron following the administration of DLCHb to swine. Swine were dosed (2 g/kg) with 10 g/dL DCLHb, infused intravenously at a rate of 1 mL/kg/min. Blood samples were collected up to 48 hours post-infusion for analysis. Tissue samples were obtained for iron determination. The data collected showed that the concentration of DCLHb in the plasma gradually decreased, while the concentration of methemoglobin remained low and essentially constant. The oxygen binding characteristics and stability of the crosslink were preserved following infusion, indicating that the DCLHb continued to function as an effective oxygen carrier. Iron concentrations in the liver and kidneys increased as expected, but plasma levels of iron did not saturate the iron binding capacity of transferrin, inferring a controlled process for the release of iron.

Animals↗
PubMed1994

Diaspirin crosslinked hemoglobin (DCLHb) polymerization.

By employing proprietary polymerization agents possessing specific binding groups and by completing diaspirin crosslinked hemoglobin (DCLHb) polymerization under specific conditions, we have selectively achieved the following objectives: (1) the P50 was adjusted to the physiologic range or left- or right-shifted; (2) the surface of DCLHb was modified ("decorated"); (3) DCLHb was polymerized but not decorated; (4) DCLHb was polymerized and decorated; or (5) DCLHb was site-specifically modified and polymerized.

Amino Acids, Diamino↗
PubMed1993

A phase I/II study of intraoperative radiotherapy in advanced unresectable or recurrent carcinoma of the rectum: a Radiation Therapy Oncology Group (RTOG) study.

The Radiation Therapy Oncology Group (RTOG) initiated a phase I/II study of intraoperative radiotherapy (IORT) in advanced or recurrent rectal cancer to assess therapeutic efficacy, toxicity, and establish quality control guidelines prior to beginning a phase III trial. From October 1985 through December 1989, 87 patients with histologically proven adenocarcinoma of the rectum or rectosigmoid with recurrent/persistent disease after surgery or those primarily inoperable were entered by 14 institutions. Of 86 evaluable patients, 42 patients received IORT either alone (n = 15) or in combination with external beam (n = 27). Local control was dependent on the amount of residual disease prior to IORT, with 2-year actuarial local control of 77% if no gross residual disease remained vs. 10% with gross residual disease (P = 0.001). For the recurrent/residual group (n = 33), this observation was also significant with a 2-year actuarial local control rate of 64% if no gross residual remained vs. 10% with gross residual disease (P = 0.004). Local control translated into an improved survival for all patients and the recurrent/residual group with 2-year actuarial survival of 88% and 89% if no gross residual disease remained vs. 48% and 45% with gross residual disease, respectively (P = .0005, 0.006). Six patients (14.6%) experienced four grade 3 and three grade 4 complications as a possible result of IORT during follow-up with a 2-year actuarial risk of major complications of 16%. We conclude that IORT is feasible within a cooperative group and can be performed with acceptable complication rates. A phase III trial to demonstrate a therapeutic advantage for IORT over external beam alone is currently in progress.

Actuarial Analysis↗
PubMed1993

Characterization of three overlapping deletions causing X-linked lymphoproliferative disease.

Blot hybridization was used to find DNA sequences missing in a male who lacked two-thirds of Xq25. The probes were used to discover two additional males with deletions resulting in X-linked lymphoproliferative disease (XLP). All three deletions have a region in common, and DXS739 is within this candidate region. The new deletions were also detectable using chromosome banding, and the smallest removes only one-third of Xq25. XLP is the only consequence of the deletions.

Adult↗
PubMed1993

High-resolution mapping of probes near the X-linked lymphoproliferative disease (XLP) locus.

Fluorescence in situ hybridization (FISH) was employed in high-resolution mapping of probes near the X-linked lymphoproliferative disease (XLP) locus. The map includes the DXS42, DXS12, DXS6, DXS982, DXS739, DXS75, DXS100, DXS10, and DXS177 loci. Metaphase analysis showed that DXS12 and DXS42 mapped to proximal Xq25, while DXS10 and DXS177 mapped to proximal Xq26.1. DXS6, DXS982, DXS739, DXS75, and DXS100 were in Xq25. The order of probes deduced from interphase FISH was: Xq24-(DXS12, DXS42)-DXS6-DXS982-DXS739-DXS75-DXS100+ ++-DXS10-DXS177-Xq26.2. We estimate that the entire region between DXS12 and DXS177 is about 7 Mb. Our previous study indicated that all three XLP deletions (63-3, 66-1, and 43-4) lacked DXS739. We now report that DXS75 and DXS982 are also missing in these deletions. Using interphase FISH measurements, we estimate that 2 Mb are absent in 63-3, and 4 Mb are absent in 66-1 and 43-4. This FISH map confines the XLP candidate gene region to a 2-Mb interval between DXS6 and DXS100 and places DXS100 distal to the XLP locus. This study also demonstrates that small probes (0.6 to 3.6 kb) can be utilized in FISH.

Chromosome Deletion↗
PubMed1993

Ruptured abdominal aortic aneurysms in a private hospital: a decade's experience (1980-1989).

Despite refinements in elective resection of abdominal aortic aneurysms, morbidity and mortality rates for ruptured abdominal aortic aneurysms (RAAAs) remain high. Between January 1, 1980 and December 31, 1989, we treated 208 patients with RAAAs whose mean age was 70 years. The overall mortality rate was 49.5%. Logistic regression analysis showed that three factors correlated with predicted patient survival. Patients < 70 years old had a survival rate of 65.7% compared with a survival rate of 37.4% in patients > 70 years old (p < 0.001). Among "stable" patients (preoperative blood pressure consistently > 90 mm Hg), 88.9% survived compared with 40.9% of "unstable" patients (blood pressure < 90 mm Hg) (p < 0.001). Of the patients with free intraperitoneal rupture, 38.3% survived compared with a survival rate of 79.6% of patients with rupture confined to the retroperitoneum (p < 0.001). Despite a high overall mortality rate in patients with RAAAs, surgical intervention remains the only hope for survival. We continue to advocate an aggressive surgical approach in this group of patients.

Aged↗
PubMed1993

Optimizing the use of nursing pool resources.

The use of per diem staff is a popular method of meeting staffing deficiencies related to fluctuations in volume and intensity of nursing service. The authors describe the reorganization of a nursing pool. This restructuring resulted in an increase of available pool hours, a decrease in overtime and agency use, and significant savings related to orientation costs.

Florida↗
PubMed1993

Influence of subinhibitory levels of antibiotics on expression of Escherichia coli lipopolysaccharide and binding of anti-lipopolysaccharide monoclonal antibodies.

The expression of Escherichia coli lipopolysaccharide (LPS) and the binding capacity of anti-LPS monoclonal antibodies (MAbs) to E. coli grown in the presence or absence of subinhibitory concentrations of various antibiotics was studied. Four E. coli strains (three clinical blood-culture isolates and an isogenic, non-capsulate mutant of the O18:K1 parent) were grown in the presence of the beta-lactam antibiotic, ampicillin, the aminoglycoside gentamicin, the fluoroquinolone ciprofloxacin and chloramphenicol. The techniques of silver staining, immunoblotting, whole-cell ELISA and flow cytometry were all used to monitor the expression of LPS on the bacteria and the binding of the anti-LPS MAbs. Treatment with ampicillin, chloramphenicol and ciprofloxacin resulted in enhanced binding of anti-core reactive MAbs to most E. coli strains. Overall, treatment with gentamicin produced the least effect on MAb binding. The presence of chloramphenicol decreased the expression of high molecular mass O-antigen or increased the expression of low molecular mass substituted E. coli LPS or both. These results further illustrate that LPS core, especially the inner-core region, becomes more accessible to antibodies when bacteria are grown in the presence of certain antibiotics. Possible synergy between antibodies and antibiotics for treatment of septicaemia and septic shock remains an intriguing possibility.

Ampicillin↗
PubMed1993

Cerebral aspartate utilization: near-equilibrium relationships in aspartate aminotransferase reaction.

The pathways of nitrogen transfer from 50 microM [15N]aspartate were studied in rat brain synaptosomes and cultured primary rat astrocytes by using gas chromatography-mass spectrometry technique. Aspartate was taken up rapidly by both preparations, but the rates of transport were faster in astrocytes than in synaptosomes. In synaptosomes, 15N was incorporated predominantly into glutamate, whereas in glial cells, glutamine and other 15N-amino acids were also produced. In both preparations, the initial rate of N transfer from aspartate to glutamate was within a factor of 2-3 of that in the opposite direction. The rates of transamination were greater in synaptosomes than in astrocytes. Omission of glucose increased the formation of [15N]-glutamate in synaptosomes, but not in astrocytes. Rotenone substantially decreased the rate of transamination. There was no detectable incorporation of 15N from labeled aspartate to 6-amino-15N-labeled adenine nucleotides during 60-min incubation of synaptosomes under a variety of conditions; however, such activity could be demonstrated in glial cells. The formation of 15N-labeled adenine nucleotides was marginally increased by the presence of 1 mM aminooxyacetate, but was unaffected by pretreatment with 1 mM 5-amino-4-imidazolecarboxamide ribose. It is concluded that (1) aspartate aminotransferase is near equilibrium in both synaptosomes and astrocytes under cellular conditions, but the rates of transamination are faster in the nerve endings; (2) in the absence of glucose, use of amino acids for the purpose of energy production increases in synaptosomes, but may not do so in glial cells because the latter possess larger glycogen stores; and (3) nerve endings have a very limited capacity for salvage of the adenine nucleotides via the purine nucleotide cycle.

Adenine Nucleotides↗