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Biomedical subjects

E Collier

Publications and source records attributed to E Collier.

At least 19 recordsLinked to original sources
PubMed2003

A study on the experience of insomnia in a psychiatric inpatient population.

Complaints of insomnia among psychiatric inpatients are high. Many technical studies about insomnia are available in the literature, but few make reference to individual experience. This study examines the subjective experience of insomnia for psychiatric patients in one mental health unit. A random purposive sample of seven subjects was selected from the population of patients complaining of insomnia. Subjective experience was examined using a tape-recorded semistructured interview. The data were analysed using Burnard's content analysis framework. Ten categories were identified: control, wants and desires, holistic, assessment, individualisms, beliefs, conflict, communication, resignation and sleep signatures. Biographical data, and data from clinical notes about sleep were also collected. Results show that the impact of insomnia should not be underestimated and that attention to this aspect of a patient's experience could have a general effect on their mental health and well-being.

Adaptation, Psychological↗
PubMed1998

Preoxygenation before laryngoscopy in children: how long is enough?

The ideal preoxygenation period prior to laryngoscopy in children is unclear. This study was performed to determine an appropriate duration of preoxygenation for infants and children prior to laryngoscopy using endtidal oxygen (FE'O2) criteria. Healthy paediatric patients for elective day surgery procedures were studied. An inflatable mask connected to an oxygen-primed paediatric anaesthesia semiclosed circuit was placed on the face while patients breathed spontaneously during 6.min-1 oxygen flow. An FE'O2 of 0.9 was considered the endpoint, and if not achieved in two min the protocol was ended. Fifty-eight children were studied. Six patients never achieved an FE'O2 of 0.9 and were not considered in the analysis. The times (in seconds with mean +/- SD and range) to achieve a minimum endtidal (FE'O2) of 0.9 for under six months were 36 +/- 11.4(20-50), 7-12 months were 35.5 +/- 13.3(20-60), 13-36 months were 42.6 +/- 18.7(20-90), 37-60 months were 50.8 +/- 18.5(30-90), > 60 months were 68.4 +/- 24.1(30-100). Logistic regression curves were determined for each age group describing the probability of achieving an FE'O2 of 0.9 against time of preoxygenation. All children with satisfactory mask fit were able to preoxygenate to an FE'O2 of 0.9 within 100 s.

Ambulatory Surgical Procedures↗
PubMed1997

Beneficial impact of aorto-coronary graft markers on post-operative angiography.

OBJECTIVE: When coronary and graft angiography is required for patients with prior coronary artery bypass (CAB) graft surgery, it is often difficult to localize the proximal aorto-coronary graft anastamosis. Our goal was to quantify the potential benefit during subsequent angiography if the proximal anastamosis is marked by an aorto-coronary graft marker at the time of CAB. METHODS: Retrospective review of 414 angiograms that were performed for patients with prior CAB. Cohorts with an without graft markers were compared. RESULTS: In the group with aorto-coronary graft markers and > or = 2 aorto-coronary grafts, there were significant reductions in fluoroscopy time (30.5%, p < 0.0001), contrast volume (21.7%, p < 0.0001), and numbers of angiographic catheters used (17.0%, p = 0.0001). If only one aorto-coronary graft was placed and marked, a trend toward reduced fluoroscopy time was observed (23.8%, p = 0.07). CONCLUSIONS: This study demonstrates the objective benefit supporting routine placement of circumferential aorto-coronary graft markers during CAB, particularly if > 1 graft is required.

Anastomosis, Surgical↗
PubMed1995

Localization of insulinomas to regions of the pancreas by intra-arterial stimulation with calcium.

OBJECTIVE: To determine the sensitivity of calcium injected into pancreatic arteries in localizing insulin-secreting tumors to regions of the pancreas. DESIGN AND PATIENTS: To stimulate the release of insulin, 25 patients with surgically proven insulinomas (average diameter, 15 mm) had calcium gluconate (0.025 mEq Ca++/kg body weight) injected before surgery into the arteries supplying the pancreatic head (gastroduodenal and superior mesenteric arteries) and the body and tail (splenic artery) of the pancreas. SETTING: Tertiary referral hospital. MEASUREMENTS: Insulin levels were measured in samples taken from the right and left hepatic veins before and 30, 60, and 120 seconds after calcium injection. A twofold increase in insulin level in the sample taken from the right hepatic vein 30 or 60 seconds after injection localized the insulinoma to the segment of the pancreas supplied by the selectively injected artery. Localization done using calcium stimulation was compared with localization done using transcutaneous ultrasonography (n = 22), computed tomography (n = 23), magnetic resonance imaging (n = 21), arteriography (n = 25), and portal venous sampling (n = 9). RESULTS: Calcium stimulation localized 22 of 25 insulinomas (sensitivity, 88% [95% CI, 68% to 97%]) to the correct region of the pancreas. The sensitivities of the other imaging methods were 9% for ultrasonography (CI, 1% to 23%), 17% for computed tomography (CI, 5% to 39%), 43% for magnetic resonance imaging (CI, 22% to 66%), 36% for arteriography (CI, 18% to 57%), and 67% for portal venous sampling (CI, 30% to 93%). Calcium stimulation added only a few minutes to the time needed for pancreatic arteriography and caused no morbid conditions. CONCLUSION: Intra-arterial calcium stimulation with right hepatic vein sampling for insulin gradients is the most sensitive preoperative test for localizing insulinomas.

Adult↗
PubMed1994

Mutational analysis of the NH2-terminal glycosylation sites of the insulin receptor alpha-subunit.

The insulin receptor is synthesized as a single chain of 190 kiloDaltons, which is processed to disulfide-linked mature alpha- and beta- subunits, containing N- and O-linked oligosaccharides and fatty acids. Previously (Collier E, Carpentier J-L, Beitz L, Caro LHP, Taylor SI, Gorden P: Biochemistry 32:7818-23, 1993), site directed mutagenesis of the asparagine in the first four sites of N-linked glycosylation to glutamine resulted in a receptor that was retained in the endoplasmic reticulum and not processed past the proreceptor form. In this study, mutation of these sites individually and in various combinations is studied. Mutation in the first or second glycosylation site does not significantly impair processing of the receptor; the receptor is found on the cell surface and binds insulin normally. If both the first and second sites are mutated, a significant reduction occurs in the amount of receptor found on the cell surface and in insulin binding. There is some processing of the receptor in cells expressing this mutant compared with the four-part mutant. If only the third and fourth sites are mutated, processing is impaired less than in the mutant with the first and second sites mutated. However, the amount of receptor found on the cell surface is less than in the mutant of only the first or only the second site. In all of these glycosylation mutants, the amount of receptor on the cell surface correlates with the level of 125I-labeled insulin binding on the cell surface.(ABSTRACT TRUNCATED AT 250 WORDS)

3T3 Cells↗
PubMed1993

Specific glycosylation site mutations of the insulin receptor alpha subunit impair intracellular transport.

The insulin receptor is a transmembrane protein found on multiple cell types. This receptor is synthesized as a 190-kDa proreceptor which is cleaved to produce mature alpha and beta subunits. The proreceptor contains 18 potential sites for N-linked glycosylation: 14 on the alpha subunit and 4 on the beta subunit. The codons for asparagine in the first four sites at the amino terminus of the alpha subunit were mutated to code for glutamine. This mutant receptor cDNA was stably transfected into NIH 3T3 cells. The insulin receptor produced in these cells remained in the proreceptor form; no mature alpha and beta subunits were produced. The proreceptor was slightly smaller on SDS-PAGE gels than the wild-type proreceptor and contained four less oligosaccharide chains by tryptic peptide mapping. The carbohydrate chains on the mutant proreceptor remained endoglycosidase H sensitive. However, in the presence of brefeldin A, these oligosaccharide chains could be processed to endoglycosidase H resistant chains. By immunofluorescence, the mutant proreceptor was shown to be localized to the endoplasmic reticulum. No insulin receptors could be found on the cell-surface either with cell surface labeling with biotin or with 125I-insulin binding. Thus, glycosylation of the first four N-linked glycosylation sites of the insulin receptor is necessary for the proper processing and intracellular transport of the receptor. This is in contrast to glycosylation at the four sites on the beta subunit which appear not to be important for processing but necessary for signal transduction. Therefore, N-linked glycosylation of the insulin receptor at specific sites has multiple distinctive roles.

3T3 Cells↗
PubMed1992

Characterization of purified autoantibodies to the insulin receptor from six patients with type B insulin resistance.

Anti-insulin-receptor autoantibodies are present in the serum of patients with the type B syndrome of extreme insulin resistance. Sera from six patients with this syndrome were purified over protein-A agarose to remove insulin and other serum factors and obtain an immunoglobulin fraction. These purified fractions were used to quantitatively determine the antibodies' activity in three separate assays. The ability to inhibit insulin binding was determined in an assay using fibroblasts that overexpress the human insulin receptor; the ability to immunoprecipitate the receptor was determined in an assay using biosynthetically labeled insulin receptors rather than insulin cross-linked receptors; and the ability to stimulate glucose oxidation was determined in isolated adipocytes. We show that the ability of these antibodies to inhibit insulin binding is tightly coupled to their ability to immunoprecipitate the biosynthetically labeled receptor, but neither assay predicts the bioactivity of these immunoglobulins. We suggest that the inability to show this tight coupling in the past may be due to methodological differences. We find no evidence that these antibodies are anti-idiotypic antibodies.

3T3 Cells↗
PubMed1991

O-linked oligosaccharides on insulin receptor.

The insulin receptor, an integral membrane glycoprotein, is synthesized as a single-chain precursor that is cleaved to produce two mature subunits, both of which contain N-linked oligosaccharide chains and covalently linked fatty acids. We report that the beta-subunit also contains O-linked oligosaccharides. The proreceptor, alpha-subunit, and beta-subunit were labeled with [3H]mannose and [3H]galactose in the presence or absence of an inhibitor of O-linked glycosylation. Tryptic peptides from each component were separated by reverse-phase high-performance liquid chromatography. N- and O-linked oligosaccharide chains were identified on these peptides by specific enzymatic digestions. The proreceptor and alpha-subunit contained only N-linked oligosaccharides, whereas the beta-subunit contained both N- and O-linked oligosaccharides. The O-linked oligosaccharide chains were attached to a single tryptic fraction of the beta-subunit, which also contained N-linked chains. This fraction was further localized to the NH2-terminal tryptic peptide of the beta-subunit by specific immunoprecipitation with an anti-peptide antibody with specificity for this region. Binding of insulin and autophosphorylation of the beta-subunit were not dependent on O-linked glycosylation, because cells grown in the presence of the inhibitor exhibited a normal dose response to insulin. Therefore, the insulin receptor contains O-linked oligosaccharides on the NH2-terminal tryptic peptide of the beta-subunit, and these O-linked oligosaccharides are not necessary to the binding or autophosphorylation function of the receptor.

Acetylgalactosamine↗
PubMed1987

Effects of castanospermine and 1-deoxynojirimycin on insulin receptor biogenesis. Evidence for a role of glucose removal from core oligosaccharides.

The insulin proreceptor is a 190-kDa glycoprotein that is processed to mature alpha (135-kDa) and beta (95-kDa) subunits. In order to determine the role of carbohydrate chain processing in insulin receptor biogenesis, we investigated the effect of inhibiting glucose removal from core oligosaccharides of the insulin proreceptor with glucosidase inhibitors, castanospermine and 1-deoxynojirimycin. Cultured IM-9 lymphocytes treated with inhibitors had 50% reduction in surface insulin receptors as demonstrated by ligand binding, affinity cross-linking with 125I-insulin, and lactoperoxidase/Na 125I labeling studies. Degradation rates of surface labeled receptors were similar in both control and inhibitor-treated cells (t1/2 = 5 h); thus, accelerated receptor degradation could not account for this reduction. Biosynthetic labeling experiments with [3H]leucine and [3H]mannose identified an apparently higher molecular size proreceptor (approximately 205 kDa) that failed to show the characteristic decline with time as seen in the normal 190-kDa proreceptor. Along with this finding, the biosynthetic label appearing in the mature subunits was reduced in these inhibitor-treated cells. Endoglycosidase H treatment of both precursors produced identical 170-kDa bands. Carbohydrate chains released from the 205-kDa precursor by endoglycosidase H migrated in the same position as the Glc2-3Man9GlcNAc standards when separated by high performance liquid chromatography, whereas the 190-kDa proreceptor oligosaccharides migrated similar to the Man7-9GlcNAc chains. Although the mature subunits of control and inhibitor-treated cells demonstrated equal electrophoretic mobility, the endoglycosidase H-sensitive oligosaccharides of the mature subunits in treated cells also contained residues that migrated similar to the Glc2-3Man9GlcNAc standards. Thus, glucose removal from core oligosaccharides is apparently not necessary for the cleavage of the insulin proreceptor, but does delay processing of this precursor, which probably accounts for the reduction in cell-surface receptors.

1-Deoxynojirimycin↗
PubMed1987

Partial purification and characterization of an insulin-like material from spinach and Lemna gibba G3.

The existence in invertebrates, unicellular eukaryotes, and prokaryotes of materials that resemble several vertebrate peptide hormones led to the suggestion that these peptide messengers may have arisen earlier in evolution than had previously been thought. Consistent with this hypothesis, we describe here material in two plants, spinach and Lemma gibba G3, that is very similar to mammalian insulin, yet distinctive. In each of the early purification steps, which consisted of acidic methanol chloroform extraction and sequential chromatography on C-18 hydrophobic resin, Sephadex G-50, CM-Sepharose, and a short C-3 high performance liquid chromatography column, the immunoactive material from plants resembled the common vertebrate insulins. The protein nature of the material was suggested by its destruction by Pronase but not by the inactivated enzyme. In addition, on TSK chromatography it eluted in a position similar to that of insulin, i.e. equivalent to a protein of 6000 daltons. Using an isocratic high performance liquid chromatography system, the plant immunoactivity eluted earlier, and thus was more hydrophilic, than most of the common mammalian insulins, including pork insulin. The interaction of the plant material with anti-insulin antibodies in a radioimmunoassay was confirmed by using an affinity column of anti-insulin antibodies which adsorbed the plant immunoactivity at neutral pH, and released the material with acid elution. Using a quantitative double radioimmunoassay, the plant insulin-like material was distinguished immunologically from chicken insulin. Although the plant insulin-like material is clearly distinct from pork insulin chromatographically, and from chicken insulin immunologically, it resembles vertebrate insulins in its overall configuration. The plant insulin-like material bound to insulin receptors on IM-9 lymphocytes and stimulated glucose oxidation and lipogenesis in isolated adipocytes from young rats. The bioactivity was neutralized in the presence of anti-insulin antibodies, but not in the presence of normal guinea pig IgG. The role of this insulin-like material in plants is unknown but its existence is consistent with an early evolutionary origin of the insulin messenger peptide family. Alternatively we cannot exclude a later convergent development of this family or introduction of vertebrate DNA into plants.

Biological Assay↗
PubMed1987

Myristyl and palmityl acylation of the insulin receptor.

The presence of covalently bound fatty acids in the insulin receptor has been explored in cultured human (IM-9) lymphocytes. Both alpha (Mr = 135,000) and beta (Mr = 95,000) subunits of the receptor incorporate [3H]myristic and [3H]palmitic acids in a covalent form. The effects of alkali and hydroxylamine on the labeled subunits indicate the existence of two different kinds of fatty acid linkage to the protein with chemical stabilities compatible with amide and ester bonds. The alpha subunit contains only amide-linked fatty acid while the beta subunit has both amide- and ester-linked fatty acids. Analysis by high performance liquid chromatography after acid hydrolysis of the [3H]myristate- and [3H]palmitate-labeled subunits demonstrates the fatty acid nature of the label. Furthermore, both [3H]myristic and [3H]palmitic acids are found attached to the receptor subunits regardless of which fatty acid was used for labeling. The incorporation of fatty acids into the insulin receptor is dependent on protein synthesis and is also detectable in the Mr = 190,000 proreceptor form. Fatty acylation is a newly identified post-translational modification of the insulin receptor which may have an important role in its interaction with the membrane and/or its biological function.

Acylation↗
PubMed1987

Foot care.

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Foot Diseases↗
PubMed1985

Somatostatin-like material is present in flowering plants.

Extracts of spinach contain somatostatin (SRIF)-related material (6-80 pg/g wet wt). The SRIF-related material, when purified on HPLC, was recovered as two major mol wt forms; one that eluted with a retention time similar to that of synthetic SRIF-28 and reacted in both N- and C-terminal-specific immunoassays, and a second peak that eluted with a retention time similar to that of SRIF-14 and reacted only in the C-terminal immunoassays. The purified material was active in a sensitive bioassay, and the bioactivity was neutralized in the presence of anti-SRIF antiserum. Since we have previously described the presence of similar material in bacteria, we also tested extracts of the flowering plant Lemna gibba G3, which was grown under sterile conditions. The Lemna extracts also had SRIF-related material (3.0 pg/g wet wt). Since plants are probably derived evolutionarily from unicellular organisms, the presence of SRIF-like material in higher plants gives support for the hypothesis that vertebrate-type peptide hormones have early evolutionary origins.

Animals↗