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Biomedical subjects

C Warren

Publications and source records attributed to C Warren.

At least 37 records · Page 2Linked to original sources
PubMed1992

Activity of crystalline turkey egg white lysozyme.

Hexagonal crystals of turkey egg white lysozyme have been examined for activity in order to evaluate their potential for use in time-resolved X-ray crystallographic experiments. Substrates used in this study were hexa-N-acetylglucosamine (hexa-GlcNAc) and a modified analogue of hexa-GlcNAc where the terminal sugar ring was opened by reduction with tritiated sodium borohydride. This gave a labeled beta-N-acetylglucosaminitol unit at the sixth position of the sugar chain and allowed easy quantitation of enzymatic cleavage on TLC plates. Using these substrates, it has been shown that turkey egg white lysozyme is enzymatically active in the crystal. Enzyme dispersed in the buffer surrounding the crystal does not show detectable activity under conditions relevant to an X-ray experiment. Unmodified hexa-GlcNAc is hydrolyzed into di-, tri-, and tetrasaccharides in the crystal. This cleavage pattern is different from that obtained with hen egg white lysozyme in solution and likely causes of the differences are discussed. The reduced radiolabeled oligosaccharide has a unique cleavage pattern with trisaccharides as the products. The specific activity of the enzyme with the radiolabelled analogue was 9.8 (+/- 1.0) x 10(-7) mmol/min/mg protein at 22 degrees C in the crystal.

Animals↗
PubMed1992

Helicopter doctors?

All roadside procedures carried out by doctors of the Royal London Hospital Helicopter Emergency Medical Service were recorded. Of 100 injured patients treated consecutively, 68 patients required 73 treatments or procedures that were beyond the current training of the ambulance paramedic in the United Kingdom. Doctors are therefore an essential part of HEMS operations and allow earlier live-saving medical intervention in the prehospital phase of care.

Aircraft↗
PubMed1992

Human serum and urine glycosaminoglycans in health and in patients with chronic renal failure.

Quantitation of uronic acid precipitable by cetylpyridinium chloride (CPC) and electrophoretic separation of glycosaminoglycans were performed on sera from patients with chronic renal failure and compared to normal controls. Serum CPC-precipitable uronic acid (CpUA) levels in patients with renal failure were significantly higher (mean 13.7 mg/L, range 7.1-23.6 mg/L) than normal controls (mean 9.6 mg/L, range 5.1-13.9 mg/L) due to increased concentrations of low sulphated chondroitin sulphate. A positive correlation between serum CpUA and creatinine was found in renal failure patients. Urine CpUA excretion was raised in renal failure patients compared to normal controls with an increased excretion of chondroitin sulphate (Ch-S) of reduced electrophoretic mobility. Heparan sulphate (HS), a major glycosaminoglycan in normal urine, was absent from the urine of these patients. The possible origin of urine glycosaminoglycans and the role of the kidney in glycosaminoglycan metabolism are discussed.

Adolescent↗
PubMed1992

The Royal London Hospital Helicopter Emergency Medical Service: first phase 1990.

A Helicopter Emergency Medical Service (HEMS) has been introduced to improve trauma care in the Southeast of England. The majority of the workload comes from the area bounded by the M25 ring road. In 1989 a Dauphin 365N helicopter equipped for pre-hospital primary rescue and emergency inter-hospital secondary transfer was certified by the Civil Aviation Authority. The helicopter commenced carrying patients with a paramedic and a doctor on board early in 1990. In September 1990 this service was further improved by the opening of a helipad at the Royal London Hospital and a designated HEMS desk at London Ambulance Service central control. Eighty-four patients were transported in primary rescue missions and 107 as emergency transfers in 1990.

Aircraft↗
PubMed1991

4-Quinolone-resistant Neisseria gonorrhoeae in the United Kingdom.

The auxotype, serogroup and antimicrobial susceptibility of 977 clinical isolates of Neisseria gonorrhoeae obtained at St Thomas' Hospital, London, during 1989 were determined; 23 isolates from 15 patients were resistant to 4-quinolones. Twelve of the patients acquired their infection in the UK and these strains were generally sensitive to other antimicrobial agents; strains from 10 patients were of serogroup IB-6. Three patients acquired their strains outside the UK and these isolates were multi-resistant and of different serogroups.

Ciprofloxacin↗
PubMed1990

DNA methylation in the Alcohol dehydrogenase-1 gene of maize.

Using a battery of methylation-sensitive restriction enzymes, cytosine methylation at 23 sites in a 7.6 kb region surrounding the Alcohol dehydrogenase-1 (Adh1) gene was measured in DNA prepared from immature maize cobs. Both the 5' upstream region and the entire coding region were hypomethylated in the two alleles examined. Methylation in Adh1 is independent of changes in Mutator transposable element methylation. The role of DNA methylation in Adh1 gene regulation is discussed.

Alcohol Dehydrogenase↗
PubMed1989

Developmental and genetic aspects of Mutator excision in maize.

The regulation of excision of Mu elements of the Mutator transposable element family of maize is not well understood. We have used somatic instability of Mu receptor elements from the Bronze 1 and Bronze 2 loci to monitor the frequency and the timing of excision of Mu elements in several tissues. We show that spot size in the aleurone of a bz2::mu1 stock varies between one to approximately 256 cells. This indicates that excision events begin eight divisions prior to full aleurone differentiation and end after the last division of the aleurone. We show that excision is equally biased for late events in all other tissues studied. A locus on chromosome 5 has been identified that affects spot size, possibly by altering the timing of Mu excision. Using somatic excision as an assay of Mutator activity, we found that activity can change in small sectors of the tassel; however, there are no overall activity changes in the tassel during the period of pollen shedding. We also report the recovery of germinal revertants for the bz1::mu1 and bz2::mu1 alleles. One of these revertant alleles was characterized by Southern blot analysis and found to be similar to the progenitor of the mutable allele.

Alleles↗
PubMed1988

Regulation of mutator activities in maize.

We discuss the properties of the Mutator (Mu) transposable element family of maize. We report the cloning of bz2-mu1, a mutable allele containing a 1.4-kb Mu element, using a combination of transposon tagging and tests for differential hybridization to northern and Southern blots. We report the sequence of this allele and the Mu element insertion, and propose a model for the structure of the Bz2 locus. We discuss the relationship between increased DNA modification of Mu elements and loss of somatic instability at bz2-mu1. To further explore this aspect of regulation of Mutator, we have used gene-specific probes to determine the level of modification at this locus in active and inactive Mutator lines. We have also utilized CsCl density gradients to estimate the overall level of DNA modification in active and inactive lines; we find that Mu elements in active lines are hypomethylated relative to other maize nuclear DNAs examined, and that in inactive lines the level of modification in Mu elements is similar to the genome as a whole. Utilizing gamma-irradiation, we have demonstrated that inactive lines can be reactivated; this reactivation is first noted as restitution of the spotted kernel phenotype characteristic of bz2-mu1 in active Mutator lines. Hybridization analysis of DNA from reactivated plants demonstrates that the Mu elements in general, and specifically the Mu element at bz2-mu1, have the lower level of DNA modification characteristic of active lines. These results are discussed in terms of the role and timing of DNA modification in regulating Mutator activities.

Base Sequence↗
PubMed1988

Regulation of Mu element copy number in maize lines with an active or inactive Mutator transposable element system.

In the progeny of an active Mutator plant, the number of Mu elements increases on self-pollination and maintains the average parental Mu content on outcrossing to a non-Mutator line; both patterns of transmission require an increase in the absolute number of Mu elements from one generation to the next. The same average copy number of Mu elements is transmitted through the male and female, but there is wide variation in the absolute copy number among the progeny. In inactive Mutator plants-defined both by the loss of somatic instability at a reporter gene (bronze2-mu1) and by modification of the HinfI sites in the terminal inverted repeat sequences of Mu elements - the absolute copy number of Mu elements is fixed in the parent. Thus, in outcrosses Mu element number is halved, and on self-pollination Mu copy number is constant. Reactivation of somatic mutability at cryptic bz2-mu1 alleles in inactive individuals by crossing to an active line seems not to involve an increase in Mu element copy number transmitted by the inactive individual. These and other results suggest that increases in Mu copy number occur late in plant development or in the gametophyte rather than after fertilization.

DNA Transposable Elements↗
PubMed1988

Polymorphous low-grade adenocarcinoma of minor salivary gland. An immunohistochemical and clinicopathologic study.

Polymorphous low-grade adenocarcinoma (PLGA) is a minor salivary gland carcinoma usually arising intraorally, primarily in the palate. It is characterized by cytologic uniformity, histologic blandness, and a variable, infiltrating growth pattern. To date, 117 tumors have been reported but the immunohistochemical features of this neoplasm have not been adequately described. This report describes the immunohistochemical distribution of epithelial membrane antigen (EMA), carcinoembryonic antigen (CEA), high-molecular-weight keratin, muscle-specific actin (MSA), and S-100 protein in four palatal polymorphous low-grade adenocarcinomas arising in two men and two women. Three patients were treated with a combination of radiation and surgery, and one was treated with just surgery; none of the tumors recurred or metastasized. More than 90% of tumor cells in all four tumors stained with S-100 and EMA, while 75 to 95% stained with keratin. MSA staining intensity was variable; it ranged from less than 10% to 67% of tumor cells staining positively. CEA staining also was markedly variable; it ranged from very focal luminal positivity to 75% of tumor cells staining positive. The diffuse staining pattern of EMA and S-100 and the difference in staining patterns of EMA and CEA in PLGA is distinct from that found in adenoid cystic carcinoma. In the latter neoplasm, EMA and CEA staining patterns are similar and they are localized to ductal lumina; S-100 stains much less diffusely. These differences are useful in the differential diagnosis between these two tumors.

Adenocarcinoma↗
PubMed1988

Psychological effects of dieting.

Seven men and seven women, all of normal weight, were assessed by means of daily visual analogue scales for a two-week baseline period and for two weeks during which they were placed on a calorie-restricted diet. There were no significant changes in mood and no sex differences. Compared with the baseline, during the diet there were significant changes in their cognitions concerning eating: subjects were more preoccupied with thoughts about food, had strong urges to eat more frequently and were more likely to feel out of control of their eating.

Cognition↗
PubMed1987

Effects of hypothermia on brainstem auditory evoked potentials in humans.

Ten adult patients who underwent open heart surgery under induced hypothermia had brainstem auditory evoked potentials (BAEPs) recorded at 1 degree- to 2 degrees C-steps as body temperature was lowered from 36 degrees C to 20 degrees C to determine temperature-dependent changes. Hypothermia produced increased latencies of BAEP waves I, III, and V; the prolongation was more severe for the later components with the result that interpeak latencies I-III, III-V, and I-V were also prolonged. The temperature-latency relationship was nonlinear and best expressed by exponential curve. The latencies of waves I, III, V and the interpeak latency I-V increased roughly 7% for each 1 degree C drop; they doubled at a temperature around 26 degrees C. The amplitude of the BAEP components had a quasiparabolic relationship to temperature; the amplitude rose with hypothermia to 28 degrees or 27 degrees C, but decreased linearly with further cooling. All BAEP components were present at temperatures above 23 degrees C and absent below 20 degrees C. With rewarming, the changes reversed and BAEPs returned to initial prehypothermia status.

Acoustic Stimulation↗
PubMed1987

Serum hyaluronic acid in patients with disseminated neoplasm.

Hyaluronic acid concentrations were measured by a laser nephelometric assay in serum samples from 50 patients with advanced disseminated neoplasm and 50 healthy controls matched for age and sex. The identity of hyaluronic acid was confirmed by a combination of electrophoretic and enzymatic techniques. The mean serum hyaluronic acid concentration for the control group was 1.09 mg/l, with a range of 0-4 mg/l. The mean concentration for patients with neoplastic disease was 10.38 mg/l, with a range of 0-100 mg/l. Sixty two per cent of the patients with disseminated neoplasm had serum hyaluronic acid concentrations above the control range. There was no correlation between the increased concentration of hyaluronic acid and tumour type, serum bilirubin, serum alkaline phosphatase, or serum urea concentrations. There was a higher incidence of hypercalcaemia in patients with increased hyaluronic acid concentrations, but the correlation between hyaluronic acid and calcium concentrations was not significant. In view of the possible role of hyaluronic acid in cellular differentiation and morphogenesis the finding of increased hyaluronic acid concentrations in patients with advanced neoplastic disease may be of fundamental importance in cancer biology.

Adult↗
PubMed1987

Oral cholecystography and sonography of gallbladder in cholecystectomy patients.

In comparing the diagnostic specificity and sensitivity of oral cholecystography with that of sonography in 479 patients in a community hospital, the oral cholecystogram, when used with a double dose of contrast agent, showed greater specificity (1.00) and sensitivity (0.99) than the sonogram (0.54 and 0.94, respectively). Because of lower cost, the oral cholecystogram should be used as the initial diagnostic study when cholelithiasis is suspected, unless specific contraindications exist.

Adolescent↗
PubMed1986

A comparison of the homogeneous enzyme immunoassay (EMIT) autocarousel and quantitative single test (QST) systems with the radioenzymatic assay.

A comparison was made of three methods for gentamicin assay; a modification of the radioenzymatic transferase technique, which was used as the reference method; EMIT autocarousel; and EMIT quantitative single test (QST). Correlation of both EMIT systems with the radioenzymatic method and with each other gave acceptable correlation coefficients, 0.955-0.975, for the range of concentrations tested. The coefficients of variation for within assay studies were between 3.3 and 4.9 for all three methods. Both EMIT systems provided rapid results, within minutes, albeit at a higher cost than the radioenzymatic assay. The radioenzymatic technique although cheaper with regard to the cost of materials involves considerably more technical time and effort and might not be considered suitable for samples received out-of-hours. However the combination of both EMIT systems provides facilities for batch and one-off sample tests and the ease of operation and rapid results are suited to out-of-hours operation.

Costs and Cost Analysis↗