Screening for abdominal aortic aneurysms.
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Age Factors↗
Biomedical subjects
M Lewis
Publications and source records attributed to M Lewis.
Biochemical properties of the 75-kDa tumor necrosis factor receptor. Characterization of ligand binding, internalization, and receptor phosphorylation.
An expression plasmid encoding the human 75-kDa tumor necrosis factor (TNF) type 2 receptor (TNF-R2) was constructed and used to generate a stable human cell line (293/TNF-R2) overexpressing TNF-R2. Ligand binding analysis revealed high affinity binding (Kd = 0.2 nM) with approximately 94,000 +/- 7,500 sites/cell for 125I-TNF-alpha and approximately 5-fold lower affinity for TNF-beta (Kd = 1.1 nM) with 264,000 +/- 2,000 sites/cell. Cross-linking of 125I-TNF-alpha and 125I-TNF-beta to 293/TNF-R2 cells yielded predominant complexes with apparent molecular weights of 211,000 for TNF-alpha and 205,000 and 244,000 for TNF-beta, suggesting these complexes contain two or three TNF-R2 molecules. Immunoprecipitation of TNF-R2 from 32P-labeled 293/TNF-R2 cells demonstrated that the receptor is phosphorylated. The majority (97%) of 32Pi incorporation was found in serine residues with a very low level of incorporation (3%) in threonine residues. TNF-alpha treatment of 293/TNF-R2 cells did not significantly affect the degree or pattern of phosphorylation. Cell surface-bound 125I-TNF-alpha was slowly internalized by the 293/TNF-R2 cell line with a t1/2 = 25 min. Shedding of the extracellular domain of TNF-R2 was induced by 4 beta-phorbol 12-myristate 13-acetate but not by TNF-alpha or TNF-beta.
Chromatography, Affinity↗
'References'.
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Databases, Bibliographic↗
Investigation of long term problems after obstetric epidural anaesthesia.
OBJECTIVE: To examine the association between obstetric epidural anaesthesia and subsequent long term problems. DESIGN: Postal questionnaire on health problems after childbirth linked to maternity case note data. SETTING: Maternity hospital in Birmingham. SUBJECTS: 11701 women who delivered their most recent child during 1978-85 and who returned completed questionnaires. MAIN OUTCOME MEASURES: Frequencies of long term symptoms after childbirth. RESULTS: Compared with the 6935 women who did not have epidural anaesthesia the 4766 women who did more commonly experienced backache (903 (18.9%) with epidural v 731 (10.5%) without epidural), frequent headaches 220 (4.6%) v 199 (2.9%)), migraine (92 (1.9%) v 73 (1.1%)), neckache (116 (2.4%) v 112 (1.6%)), and tingling in hands or fingers (143 (3.0%) v 150 (2.2%)). The results could not be explained by correlated social or obstetric factors. The associations with head, neck, and hand symptoms were found only in women who reported backache. An excess of visual disturbances among women who had epidural anaesthesia (83 (1.7%) v 91 (1.3%)) was present only in association with migraine, but excess of dizziness or fainting (102 (2.1%) v 109 (1.6%)) was independent of other symptoms. 26 women had numbness or tingling in the lower back, buttocks, and leg, of whom 23 had had epidural anaesthesia. Of 34 women with spinal headache, nine (five after accidental dural puncture; four after spinal block) reported long term headaches. CONCLUSIONS: These associations may indicate a causal sequence, although this cannot be proved from this type of study. Randomised trials of epidural anaesthesia are required to determine whether causal relations exist.
Adult↗
Characterization of a recombinant extracellular domain of the type 1 tumor necrosis factor receptor: evidence for tumor necrosis factor-alpha induced receptor aggregation.
An expression plasmid encoding the extracellular portion of the human tumor necrosis factor (TNF) type 1 receptor (TNF-R1) was constructed and used to generate a stable cell line secreting soluble TNF-R1 (sTNF-R1). The sTNF-R1 was purified, and its biochemical properties and its interactions with human TNF-alpha were examined. SDS-PAGE resolved the purified sTNF-R1 into three bands of approximate Mr 24,200, 28,200, and 32,800. Sedimentation equilibrium analysis gave a molecular weight of 25,000 for sTNF-R1 whereas the molecular weight obtained by gel filtration chromatography was approximately 55,000-60,000. Scatchard analysis of [125I]TNF-alpha binding to sTNF-R1 revealed high-affinity binding (Kd = 93 pM), comparable to that observed for the intact receptor on whole cells. Competitive binding experiments showed that sTNF-R1 has a 50-60-fold higher affinity for TNF-alpha than for TNF-beta, in contrast to the equal affinities of TNF-alpha and TNF-beta for the full-length TNF-R1 transiently expressed in mammalian cells. The sTNF-R1 was found to block the cytotoxicity of TNF-alpha and TNF-beta on a murine L-M cell assay. The sizes of the sTNF-R1.TNF-alpha complex determined by gel filtration chromatography and sedimentation equilibrium were approximately 141 and 115 kDa, respectively. The stoichiometry of the complex was examined by Scatchard analysis, size-exclusion chromatography, HPLC separation, amino acid composition, sequence analysis, and sedimentation equilibrium. The data from these studies suggest that at least two molecules of sTNF-R1 can bind to a single TNF-alpha trimer.(ABSTRACT TRUNCATED AT 250 WORDS)
Amino Acid Sequence↗
Calculation of the free energy of association for protein complexes.
We have developed a method for calculating the association energy of quaternary complexes starting from their atomic coordinates. The association energy is described as the sum of two solvation terms and an energy term to account for the loss of translational and rotational entropy. The calculated solvation energy, using atomic solvation parameters and the solvent accessible surface areas, has a correlation of 96% with experimentally determined values. We have applied this methodology to examine intermediates in viral assembly and to assess the contribution isomerization makes to the association energy of molecular complexes. In addition, we have shown that the calculated association can be used as a predictive tool for analyzing modeled molecular complexes.
Capsid↗
Resistance to experimental autoimmune thyroiditis is correlated with the duration of raised thyroglobulin levels.
We have used the mouse model of experimental autoimmune thyroiditis (EAT) to examine the hypothesis that the strengthening of self-tolerance to thyroglobulin by exogenous mouse thyroglobulin (MTg) or stimulation of endogenous MTg secretion by thyroid-stimulating hormone (TSH) is correlated with the length of time MTg rises above the normal range. Bacterial lipopolysaccharide (LPS) treatment increases the initial half-life of MTg from about 3 hr to about 5 hr, probably interfering with its clearance by the mononuclear phagocytic (reticuloendothelial) system. By pretreating mice with LPS, a subtolerogenic MTg dose is rendered tolerogenic. Similarly the effect of TSH infusion by osmotic minipumps, which stimulates MTg secretion and also strengthens tolerance to MTg, can be enhanced by injecting LPS shortly after pump implantation. The resulting increase in MTg level (due to delayed clearance of MTg) is greater than that from TSH alone and suppresses further the animals' susceptibility to disease induction by MTg and adjuvant. Moreover, resistance following pretreatment with LPS and subtolerogenic MTg is mediated by CD4+ suppressor T cells, as shown recently for the suppression in mice given high doses of tolerogenic MTg. These experiments are in full agreement with the hypothesis and confirm that small increases in circulating MTg concentrations, which could occur physiologically, can be effective in protecting against EAT induction.
Animals↗
Molecular basis of virulence and growth of hepatitis A virus in cell culture.
The ability of engineering variants of hepatitis A virus (strain HM175) to replicate in cell culture or to cause disease in marmosets was evaluated. Virus variants were encoded by chimeric genomes constructed from infectious cDNA clones of two viruses (wild type and cell-culture-adapted) which differed in their ability to grow in vitro and to cause acute hepatitis in marmosets. Transfection and infectivity assays indicated that virus growth in vitro could be enhanced by subcloning the cell substrate prior to infection or by introducing multiple combinations of two or more mutations into the wild type genome. Various chimeric viruses induced liver enzyme elevations in marmosets, indicating that attenuation of virulence also required multiple mutations.
Animals↗
Vertebral osteomyelitis following manipulation of spondylitic necks--a possible risk.
Neurological complications of neck manipulation are well recognised but are usually due to acute vascular incidents. However, we describe two patients with cervical spondylosis, who developed staphylococcal osteomyelitis of the cervical spine with progressive tetraplegia, apparently following manipulation of the neck by a chiropractor. Although it is possible that the manipulation resulted in cervical spine trauma sufficient to cause local haemorrhage, the area becoming a nidus for infection, it is also conceivable that the patients underwent neck manipulation in an attempt to relieve pain due to an already existing osteomyelitis of the cervical spine, and the manipulation may have hastened the onset of spinal cord paralysis. Clearly, this could have occurred, as the average time between the onset of symptoms and diagnosis of vertebral osteomyelitis in most published series is about 2 months. Approximately 80% of cases of osteomyelitis occur in the 50-70 age group, a group in which cervical spondylosis is extremely common. It would seem that neck manipulation is particularly contraindicated in older patients with cervical spondylosis.
Cervical Vertebrae↗
Serum procalcitonin as an index of inhalation injury in burns.
The molecular heterogeneity of serum immunoreactive calcitonin (iCT) was analyzed from a prospective study of 41 burn patients. Using different region-specific anticalcitonin antisera, the ratio of mid-region-recognizing to carboxyl terminal-region-recognizing iCT was found to increase acutely in those who subsequently died. The highest ratios occurred in those who died early of respiratory complications. Sephadex chromatography and reversed-phase HPLC demonstrated that the serum iCT circulated predominantly in the large molecular mass prohormone form (16 kDa). In comparison, iCT of normal human lung and of normal thyroid was shown to consist primarily of smaller monomeric mass forms. Furthermore, in 12 normal volunteers who were evaluated with a calcium-pentagastrin infusion, the ratio of iCT levels did not differ from the baseline ratio despite a 50% increase in serum iCT. These results suggest that in burns, the inhalational injury-associated hypercalcitonemia is characterized by a preferential release of procalcitonin; a form of constitutive secretion. The measurement of serum procalcitonin levels would appear to be a useful prognostic indicator of the severity of inhalational injury occurring in burn patients.
Biomarkers↗
Erythropoietin levels in amniotic fluid and extraembryonic coelomic fluid in the first trimester of pregnancy.
OBJECTIVE: The aim was to measure erythropoietin levels in amniotic fluid and extraembryonic coelomic fluid from 7-12 weeks' gestation. SUBJECTS: Twenty healthy women with ultrasonographically normal first trimester pregnancies prior to surgical termination. METHODS: Paired samples of amniotic fluid and extraembryonic coelomic fluid were collected by transvaginal ultrasound guided needling. Erythropoietin was measured in both pregnancy fluids using a radioimmunoassay. RESULTS: There was a highly significant difference between erythropoietin levels in extraembryonic coelomic fluid (median level 15.45 mU/ml; range 6.8-32.1 mU/ml) and those in amniotic fluid (median 5.0 mU/ml; range < 5.0-5.8 mU/ml) (P < 0.0001; Mann-Whitney U-test). The levels of erythropoietin in maternal serum (median 15.4 mU/ml; range 5.6-29.4 mU/ml) were similar to those in the extra-embryonic coelom (P = 0.81; Mann-Whitney U-test). No relation was demonstrated between erythropoietin levels in amniotic fluid or coelomic fluid and stage of gestation. CONCLUSION: High levels of erythropoietin in coelomic fluid suggests that the hormone is involved in the process of human extraembryonic erythropoiesis. The exact regulatory role remains unknown.
Amniotic Fluid↗
cDNA clone of hepatitis A virus encoding a virulent virus: induction of viral hepatitis by direct nucleic acid transfection of marmosets.
Direct inoculation of marmoset livers with an in vitro transcription mixture containing cDNA and full-length genomic RNA transcripts of hepatitis A virus resulted in acute viral hepatitis. Elevations in serum levels of liver enzymes were correlated with appearance of antibody to hepatitis A virus. Genomes of infectious hepatitis A virus isolated from the feces of transfected marmosets contained the same mutation as the cDNA template used for transfection. Liver biopsies confirmed that the virus encoded by the cDNA clone induced histopathological changes equivalent to those caused by virulent wild-type virus.
Animals↗
Mutations in both the 2B and 2C genes of hepatitis A virus are involved in adaptation to growth in cell culture.
Oligonucleotide-directed mutagenesis of an infectious cDNA clone of wild-type hepatitis A virus was performed to determine which mutations acquired in the nonstructural 2B and 2C genes during adaptation to growth in cell culture were effective in enhancing virus growth in vitro. Results of transfection assays demonstrated that one mutation in the 2B gene and two mutations in the 2C gene were responsible for an increased efficiency in growth, but growth enhancement required the participation of at least two of the three mutations.
Animals↗
Immunological evidence that plants use both HDEL and KDEL for targeting proteins to the endoplasmic reticulum.
The epitopes of two monoclonal antibodies raised to a putative auxin receptor have been mapped. Carboxy-peptidase A digestion of the antigen, auxin-binding protein (ABP) purified from maize, completely abolished binding of antibody MAC 256 and impaired binding of MAC 259, suggesting that they both recognise C-terminal epitopes. Published sequences of ABP showed that the C terminus was KDEL, a tetrapeptide used for targeting proteins to the ER in animal cells. We have used this short homology to confirm that the two monoclonals recognise C-terminal KDEL, showing that animal KDEL proteins and synthetic KDEL peptides are recognised and that animal cell ER is stained strongly and specifically. Sucrose density gradient fractionation of maize microsomal membranes showed that plant KDEL proteins, including ABP, fractionated with markers for the endoplasmic reticulum. However, few proteins are stained by anti-KDEL monoclonals in plants. For comparison, a monoclonal antibody raised to a synthetic HDEL peptide was also used and found to stain a set of proteins in all plant species tested. The anti-HDEL and anti-KDEL monoclonals were sequence specific, staining different proteins. On density gradient fractionation HDEL proteins also banded with ER marker activities. However, the intracellular distribution of HDEL and KDEL proteins determined by immunofluorescence was different. Whereas HDEL proteins showed a distribution characteristic of plant ER, and this localisation was confirmed by immunogold labelling of ultrathin sections and electron microscopy, KDEL proteins showed strong fluorescence in discrete parts of the cell cortex. These observations are discussed in terms of the potential these monoclonal antibodies have as markers for ER and of the role ABP plays in plant cell signalling.
Amino Acid Sequence↗
Monitoring trends and determinants in cardiovascular disease in Germany: results of the MONICA Project Augsburg, 1985-1990.
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Cardiovascular Diseases↗
Validating current immunization practice with young infants.
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Bacterial Capsules↗
Individual differences in response to stress.
Observation of newborns and infants reveals individual differences in reactivity to stress. A measurement system based on threshold, dampening, and reactivation is described to assess these individual differences in the newborn period and thereafter. The three features are independent and, therefore, represent different aspects of reactivity. There is some evidence for stability of individual differences in reactivity between birth and 2 months of age. This stability is more apparent for infants who were highly reactive as newborns. The role of dispositional factors of reactivity, their stability, and the effects of the environment are discussed.
Arousal↗
[Wake up time, thrombocyte aggregation and the risk of acute coronary heart disease. The TRIMM (Trigger and Mechanisms of Myocardial Infarct) Study Group].
A circadian variation in the incidence of acute coronary artery disease (CAD) was observed, but the correlation to possible triggering external factors and pathophysiologic mechanisms is unclear. In the "Trigger and Mechanisms of Myocardial Infarction" (TRIMM) Study, 573 patients (61 +/- 10 years; 74% male) underwent a systematic interview within 2 weeks after myocardial infarction. From 8.00 to 11.00 a.m. (peak) the relative risk of myocardial infarction was 1.9 (1.6-2.3). After statistical adjustment for individual wake-time the relative risk during the initial 3 hours after awakening was 2.7 (2.2-3.3). In 24 hour studies at platelet aggregability in 10 patients with CAD the threshold concentration of ADP (from 4.8 +/- 0.8 to 2.6 +/- 0.4 mumol, p less than 0.02) and epinephrine (from 7.3 +/- 2.3 to 1.8 +/- 0.9 mumol, p less than 0.02) decreased significantly between 6.00 and 9.00 a.m. indicating an increase of aggregability. The temporal coincidence of clinical events and physiological changes suggests a causal relationship. Further possible important factors in increasing the risk of CAD during the morning include the increase of blood pressure enhancing the risk of plaque rupture and of coronary tone at the same time of day. These results are important in determining the acute mechanisms of CAD and in improving its prevention.
Aged↗