26
|
Mitchell JR, Whitney FW. The effect of injection speed on the perception of intramuscular injection pain. A clinical update. AAOHN JOURNAL : OFFICIAL JOURNAL OF THE AMERICAN ASSOCIATION OF OCCUPATIONAL HEALTH NURSES 2001; 49:286-92. [PMID: 11760527] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/23/2023]
Abstract
Injections are frequently administered by occupational health nurses in worksite health promotion programs. The purpose of this study was to examine the effect of varying injection speed on the perception of pain. Fifty workers were given intramuscular (i.m.) hepatitis B vaccine at injection speeds of 10 and 30 seconds per cubic centimeter (s/cc). The perception of pain was measured on a visual analogue scale and reported post-injection at three different time intervals. The results showed that no difference in pain was perceived by participants between the two injection speeds. Results also revealed that women consistently had higher mean pain scores than men and significantly more pain at the 0 hour measurement of the 10 s/cc injection. While the results of this study indicate no need to administer an i.m. injection slower than 10 s/cc, occupational health nurses will need to consider gender differences in pain perception when administering injections.
Collapse
|
27
|
Small CJ, Kim MS, Stanley SA, Mitchell JR, Murphy K, Morgan DG, Ghatei MA, Bloom SR. Effects of chronic central nervous system administration of agouti-related protein in pair-fed animals. Diabetes 2001; 50:248-54. [PMID: 11272133 DOI: 10.2337/diabetes.50.2.248] [Citation(s) in RCA: 126] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The melanocortin receptor (MC3-R and MC4-R) antagonist, agouti-related protein (AGRP), is a potent stimulant of food intake. We examined the effect of chronic intracerebroventricular (ICV) AGRP treatment on energy metabolism and pituitary function in ad libitum fed rats and rats administered AGRP and then pair-fed to a saline control group. Chronic ICV AGRP (83-132) administration (1 nmol/day for 7 days) significantly increased food intake and body weight in ad libitum fed animals compared with saline-treated controls (body weight on day 7: 272 +/- 6 [saline] vs. 319 +/- 8 g [AGRP ad libitum fed]; P < 0.001). A significant increase in the epididymal fat pad weight, interscapular brown adipose tissue (BAT) weight, and plasma leptin was also observed in the ad libitum fed group. In the AGRP pair-fed group, a significant increase in the epididymal fat pad weight, BAT weight, and plasma leptin was again observed, suggesting that AGRP caused metabolic changes independent of increased food intake. BAT uncoupling protein 1 (UCP-1) content was significantly decreased compared with saline controls in both the AGRP ad libitum fed (21 +/- 8% of saline control; P < 0.01) and AGRP pair-fed groups (24 +/- 7% of saline control; P < 0.01). Plasma thyroid-stimulating hormone (TSH) was significantly suppressed compared with saline controls in both the AGRP ad libitum fed and AGRP pair-fed groups (3.5 +/- 0.3 [saline] vs. 2.7 +/- 0.4 [AGRP ad libitum fed] vs. 2.1 +/- 0.2 ng/ml [AGRP pair-fed]; P < 0.01). This study demonstrates that independent of its orexigenic effects, chronic AGRP treatment decreased BAT UCP-1, suppressed plasma TSH, and increased fat mass and plasma leptin, suggesting that it may play a role in energy expenditure.
Collapse
|
28
|
Abstract
Telomerase is a ribonucleoprotein reverse transcriptase that extends the ends of chromosomes. The two telomerase subunits essential for catalysis in vitro are the telomerase reverse transcriptase (TERT) and the telomerase RNA. Using truncations and site-specific mutations, we identified sequence elements of TERT and telomerase RNA required for catalytic activity and protein-RNA interaction for Tetrahymena thermophila telomerase. We found that the TERT amino and carboxyl termini, although evolutionarily poorly conserved, are nonetheless important for catalytic activity. In contrast, high-affinity telomerase RNA binding requires only a small region in the amino terminus of TERT. Surprisingly, the TERT region necessary and sufficient for telomerase RNA binding is completely separable from the reverse transcriptase motifs. The minimal Tetrahymena TERT RNA binding domain contains two sequence motifs with ciliate-specific conservation and one TERT motif with conservation across all species. With human TERT, we demonstrate that a similar region within the TERT amino terminus is essential for human telomerase RNA binding as well. Finally, we defined the Tetrahymena telomerase RNA sequences that are essential for TERT interaction. We found that a four-nucleotide region 5' of the template is critical for TERT binding and that the 5' end of telomerase RNA is sufficient for TERT binding. Our results reveal at least one evolutionarily conserved molecular mechanism by which the telomerase reverse transcriptase is functionally specialized for obligate use of an internal RNA template.
Collapse
|
29
|
Kedward CJ, MacNaughtan W, Mitchell JR. Isothermal and non-isothermal crystallization in amorphous sucrose and lactose at low moisture contents. Carbohydr Res 2000; 329:423-30. [PMID: 11117325 DOI: 10.1016/s0008-6215(00)00179-8] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Differential scanning calorimetry has been used in isothermal and non-isothermal modes to provide information on the crystallization of sucrose and lactose at low water contents. Using approaches previously applied to polymer crystallization an attempt has been made to combine the isothermal and non-isothermal data into a single curve. This is achieved by the use of appropriate shift factors in the time and temperature domains. This was successful for sucrose but not for lactose. It was suggested that this was because lactose crystallizes into multiple forms whereas sucrose crystallizes in a single form.
Collapse
|
30
|
Kasapis S, Al-Alawi A, Guizani N, Khan AJ, Mitchell JR. Viscoelastic properties of pectin--co-solute mixtures at iso-free-volume states. Carbohydr Res 2000; 329:399-407. [PMID: 11117323 DOI: 10.1016/s0008-6215(00)00193-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Small-deformation oscillatory measurements were performed on pectin-sucrose-glucose syrup systems at a total level of solids of 81%, with the polysaccharide content being fixed at levels of industrial use (1%). The experimental temperature range was between 50 and - 50 degrees C. Analysis of the temperature dependence of viscoelastic processes by the equation of Williams, Landel, and Ferry provides values of fractional free volume for the temperatures covering the glass transition region. The shift factors used in the conversion of mechanical spectra into master curves were normalised at suitably different temperatures so that their temperature dependence becomes coincident. The treatment implies an iso-free-volume state and relates to changes in the monomeric friction coefficient with increasing levels of intermolecular interactions in the mixture. A free-volume related glass transition temperature was defined and manipulated markedly by introducing pectin of variable degrees of esterification to the sucrose-glucose syrup system.
Collapse
|
31
|
Ramesh M, Bhattacharya KR, Mitchell JR. Developments in understanding the basis of cooked-rice texture. Crit Rev Food Sci Nutr 2000; 40:449-60. [PMID: 11186235 DOI: 10.1080/10408690091189220] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
|
32
|
Mitchell JR, Baker MC. Religious commitment and the construal of sources of help for emotional problems. THE BRITISH JOURNAL OF MEDICAL PSYCHOLOGY 2000; 73 ( Pt 3):289-301. [PMID: 11003370 DOI: 10.1348/000711200160471] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Religious commitment as an influence upon seeking help for psychological problems has not received the same level of research attention as variables such as sex, ethnicity and cultural background. The construing of members of a group of committed UK Christians was investigated, regarding their receiving such help from a variety of different helpers, professional and non-professional, secular and spiritual. Each participant was asked to interpret the factors statistically identified from construct and element relationships in a repertory grid that they had completed. Their commentaries formed the data for a qualitative thematic analysis, which gave rise to four main themes. From these, a tentative model is discussed. Possible implications for the acceptance of service provision by the substantial minority groups of religiously committed people in the UK are considered in the light of this model--and in the light of the further research that would be needed to establish it.
Collapse
|
33
|
Mitchell JR, Collins K. Human telomerase activation requires two independent interactions between telomerase RNA and telomerase reverse transcriptase. Mol Cell 2000; 6:361-71. [PMID: 10983983 DOI: 10.1016/s1097-2765(00)00036-8] [Citation(s) in RCA: 191] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Inhibition or activation of the reverse transcriptase telomerase can profoundly affect the proliferative capacity of normal cells and cancers. Here, we elucidate structural requirements for function of the essential RNA component of human telomerase, hTR. Two motifs within the independently stable H/ACA domain of hTR are required for accumulation of the mature RNA in vivo. However, these motifs can be substituted by a heterologous H/ACA family RNA. Two additional hTR elements are required both in vivo and in vitro for telomerase catalytic activity. Surprisingly, each of these elements independently binds to the telomerase reverse transcriptase. Our results establish fundamental differences between vertebrate and ciliate telomerase ribonucleoprotein architectures and also suggest strategies for the pharmaceutical development of telomerase-based anticancer therapies.
Collapse
|
34
|
Gareau PJ, Rutt BK, Karlik SJ, Mitchell JR. Magnetization transfer and multicomponent T2 relaxation measurements with histopathologic correlation in an experimental model of MS. J Magn Reson Imaging 2000; 11:586-95. [PMID: 10862056 DOI: 10.1002/1522-2586(200006)11:6<586::aid-jmri3>3.0.co;2-v] [Citation(s) in RCA: 173] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Magnetization transfer and multicomponent T2 imaging techniques were implemented to study guinea pig in vivo. A chronic-progressive model of experimental allergic encephalomyelitis (EAE) was produced, and the inflammatory component of the disease was manipulated using antibodies against integrin. The magnetization transfer ratio (MTR) and T2 relaxation properties were measured in normal-appearing white matter (NAWM) with histological comparisons. Significant reductions in both the mean MTR and the myelin water percentage were measured in NAWM of EAE guinea pig brain. However, the MTR and myelin water percentage appear to measure different aspects of pathology in NAWM in EAE. Reductions in the MTR were prevented or reversed with suppression of inflammation. However, modulation of inflammatory activity was not reflected in the measurement of the myelin water percentage. Since the amount of myelin is not expected to vary with inflammatory-related changes, these observations support our hypothesis that the MTR is sensitive to physiological changes to myelin induced by inflammation, while the short T2 component is a more specific indicator of myelin content in tissue. Pathologic features other than demyelination may be important in the determination of the MTR.
Collapse
|
35
|
Russell J, Mitchell JR. The assessment of a "nurse led" deliberate selfharm service. HEALTH BULLETIN 2000; 58:221-3. [PMID: 12813830] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 03/03/2023]
Abstract
OBJECTIVE To determine the effectiveness of a nurse led deliberate selfharm assessment service. DESIGN Nine month retrospective survey and comparison with previous system. SETTING Stobhill General Hospital, North Glasgow. SUBJECTS Two hundred and eighty three Medical inpatients referred following deliberate selfharm, with completed data on 272 cases. RESULTS The service significantly reduced admissions to psychiatric inpatient care from 24% to 7%. A dedicated nurse led service, has led to consistency in parasuicide assessments, reduced stigma and negativity towards DSH patients, led to better joint working between Stobhill General Hospital and Psychiatric services and reduced inappropriate psychiatric outpatient referrals. CONCLUSIONS A dedicated nurse led DSH assessment service benefits patients and reduces psychiatric hospital admissions. A member of the psychiatric staff working on a daily basis within the general medical wards enhances joint working, ensures smoother communication between helping agencies and increases treatment options.
Collapse
|
36
|
Farhat IA, Blanshard JM, Mitchell JR. The retrogradation of waxy maize starch extrudates: effects of storage temperature and water content. Biopolymers 2000; 53:411-22. [PMID: 10738202 DOI: 10.1002/(sici)1097-0282(20000415)53:5<411::aid-bip5>3.0.co;2-m] [Citation(s) in RCA: 86] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The effects of water content and storage temperature on the kinetics of the retrogradation of nonexpanded waxy maize starch extrudates were studied using (1)H pulsed NMR and wide-angle X-ray diffraction. The increase in crystallinity observed by XRD was accompanied by a decrease in the relaxation times of the solid-like component of the NMR free induction and the spin-echo decays, and an increase in the contribution of the solid-like component to the total signal. The dependence of the rate of starch retrogradation on the storage temperature showed the typical "bell-shaped" behavior, which was successfully modeled using the Lauritzen-Hoffman theory of crystallization of chain-folded polymers. This theory was extended to model the effect of water content on the rate of isothermal crystallization by exploiting the ten-Brinke and Karasz, and the Flory equations to describe the dependence of the glass-transition and the melting temperatures on water content.
Collapse
|
37
|
Mitchell JR, Wood E, Collins K. A telomerase component is defective in the human disease dyskeratosis congenita. Nature 1999; 402:551-5. [PMID: 10591218 DOI: 10.1038/990141] [Citation(s) in RCA: 800] [Impact Index Per Article: 32.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The X-linked form of the human disease dyskeratosis congenita (DKC) is caused by mutations in the gene encoding dyskerin. Sufferers have defects in highly regenerative tissues such as skin and bone marrow, chromosome instability and a predisposition to develop certain types of malignancy. Dyskerin is a putative pseudouridine synthase, and it has been suggested that DKC may be caused by a defect in ribosomal RNA processing. Here we show that dyskerin is associated not only with H/ACA small nucleolar RNAs, but also with human telomerase RNA, which contains an H/ACA RNA motif. Telomerase adds simple sequence repeats to chromosome ends using an internal region of its RNA as a template, and is required for the indefinite proliferation of primary human cells. We find that primary fibroblasts and lymphoblasts from DKC-affected males are not detectably deficient in conventional H/ACA small nucleolar RNA accumulation or function; however, DKC cells have a lower level of telomerase RNA, produce lower levels of telomerase activity and have shorter telomeres than matched normal cells. The pathology of DKC is consistent with compromised telomerase function leading to a defect in telomere maintenance, which may limit the proliferative capacity of human somatic cells in epithelia and blood.
Collapse
|
38
|
Gareau PJ, Rutt BK, Bowen CV, Karlik SJ, Mitchell JR. In vivo measurements of multi-component T2 relaxation behaviour in guinea pig brain. Magn Reson Imaging 1999; 17:1319-25. [PMID: 10576717 DOI: 10.1016/s0730-725x(99)00064-8] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Multi-echo Carr-Purcell-Meiboom-Gill (CPMG) imaging sequences were implemented on 1.5 T and 4.0 T imaging systems to test their ability to measure in vivo multi-component T2 relaxation behavior in normal guinea pig brain. The known dependence of accurate T2 measurements on the signal-to-noise ratio (SNR) was explored in vivo by comparing T2 decay data obtained using three methods to increase SNR (improved RF coil design, signal averaging and increased magnetic field strength). Good agreement between T2 values of nickel-doped agarose phantoms was found between imaging and spectroscopic methods. T2 values were determined for gray matter (GM) and white matter (WM) locations from images of guinea pig brain in vivo. T2 measurements of GM were found to be monoexponential at both field strengths. The mean T2 times for GM were 71 ms at 1.5 T, and 53 ms at 4.0T. The highest average SNR was achieved using an improved RF coil at 4.0T. In this case, two peaks were extracted in WM, a "short" T2 peak at approximately 6 ms, and a "medium" T2 peak at approximately 48 ms. T2 values in GM and the major component of WM were significantly decreased at 4.0T compared to 1.5 T. The improved SNR attained with this optimized imaging protocol at 4.0T has allowed for the first time extraction of the myelin-sensitive T2 component of WM in animal brain in vivo.
Collapse
|
39
|
Bulut S, Waites WM, Mitchell JR. Effects of combined shear and thermal forces on destruction of Microbacterium lacticum. Appl Environ Microbiol 1999; 65:4464-9. [PMID: 10508076 PMCID: PMC91594 DOI: 10.1128/aem.65.10.4464-4469.1999] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A twin-screw extruder and a rotational rheometer were used to generate shear forces in concentrated gelatin inoculated with a heat-resistant isolate of a vegetative bacterial species, Microbacterium lacticum. Shear forces in the extruder were mainly controlled by varying the water feed rate. The water content of the extrudates changed between 19 and 45% (wet weight basis). Higher shear forces generated at low water contents and the calculated die wall shear stress correlated strongly with bacterial destruction. No surviving microorganisms could be detected at the highest wall shear stress of 409 kPa, giving log reduction of 5.3 (minimum detection level, 2 x 10(4) CFU/sample). The mean residence time of the microorganism in the extruder was 49 to 58 s, and the maximum temperature measured in the end of the die was 73 degrees C. The D(75 degrees C) of the microorganism in gelatin at 65% water content was 20 min. It is concluded that the physical forces generated in the reverse screw element and the extruder die rather than heat played a major part in cell destruction. In a rotational rheometer, after shearing of a mix of microorganisms with gelatin at 65% (wt/wt) moisture content for 4 min at a shear stress of 2.8 kPa and a temperature of 75 degrees C, the number of surviving microorganisms in the sheared sample was 5.2 x 10(6) CFU/g of sample compared with 1.4 x 10(8) CFU/g of sample in the nonsheared control. The relative effectiveness of physical forces in the killing of bacteria and destruction of starch granules is discussed.
Collapse
|
40
|
Schmidt MH, Mitchell JR, Downey DB. Sonographic surveillance of abdominal aortic aneurysms: what is the smallest change in measured diameter that reliably reflects aneurysm growth? Can Assoc Radiol J 1999; 50:241-6. [PMID: 10459310] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/13/2023] Open
Abstract
OBJECTIVE The decision to repair an abdominal aortic aneurysm may be based on an apparent increase in aneurysm diameter seen in successive sonographic examinations. However, true aneurysm growth can be diagnosed only if the measured increase in aneurysm diameter exceeds the variability inherent in the measurement. This study uses analysis of variance to determine the smallest change between 2 successive, independent sonographic measurements of aneurysm diameter that reliably indicates aneurysm growth. METHODS Pairs of independent observers examined 63 patients with abdominal aortic aneurysms. Each observer obtained a sonographic measurement of the anteroposterior aneurysm diameter in the transaxial and longitudinal scan planes, and the transverse aneurysm diameter in the transaxial scan plane. Analysis of variance yielded the total variance associated with each type of measurement as well as the contributions made by variance among aneurysms, variance between observers and residual variance. These components were used to estimate interobserver standard error of measurement, interobserver reliability and the smallest measurement change needed to diagnose true aneurysm growth. RESULTS Differences among aneurysms made the largest contribution to overall variance. Interobserver reliability was excellent, ranging from 0.89 to 0.94 (with perfect reliability being 1.00). The smallest difference between 2 successive, independent anteroposterior diameter measurements that indicated aneurysm growth at the 95% confidence level was 0.78 cm in the transaxial scan plane and 0.92 cm in the longitudinal scan plane. The smallest difference between 2 successive, independent transverse diameter measurements that indicated aneurysm growth at the same confidence level was 1.05 cm. CONCLUSION Despite high interobserver reliability, only changes in measured aneurysm diameter greater than or equal to 0.78 cm indicate aneurysm growth at the 95% confidence level. Smaller changes in measured diameter may not be real, but due to variability in measurement.
Collapse
|
41
|
Gareau PJ, Gati JS, Menon RS, Lee D, Rice G, Mitchell JR, Mandelfino P, Karlik SJ. Reduced visual evoked responses in multiple sclerosis patients with optic neuritis: comparison of functional magnetic resonance imaging and visual evoked potentials. Mult Scler 1999; 5:161-4. [PMID: 10408715 DOI: 10.1177/135245859900500304] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The limited application of functional magnetic resonance imaging (fMRI) for investigations of multiple sclerosis (MS) patients has already shown that deficits of the motor, cognitive and visual systems may be identified by differences in the patterns of activation in response to a suitable stimulus. In MS patients with unilateral optic neuritis, the area of activation in the primary visual cortex, measured by fMRI techniques, is dramatically reduced in response to stimulation of the affected eye. The latency of the major positive component of the visual evoked potential (VEP) recorded upon stimulation of the affected eye is significantly increased in these patients, as compared to the unaffected eye and normal volunteers. We have found a correlation between the neural response measured using fMRI and the latency of the VEP. fMRI signal responses have the potential to provide more detailed topographic information relating to functional deficits in MS.
Collapse
|
42
|
Mitchell JR, Cheng J, Collins K. A box H/ACA small nucleolar RNA-like domain at the human telomerase RNA 3' end. Mol Cell Biol 1999; 19:567-76. [PMID: 9858580 PMCID: PMC83914 DOI: 10.1128/mcb.19.1.567] [Citation(s) in RCA: 408] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Simple sequence repeat telomeric DNA is maintained by a specialized reverse transcriptase, telomerase. The integral RNA subunit of telomerase contains a template region that determines the sequence added to chromosome ends. Aside from providing the template, little is known about the role of the telomerase RNA. In addition, no hypotheses have been suggested to account for the striking evolutionary divergence in size and sequence between telomerase RNAs of ciliates, yeasts, and mammals. We show that the two- to threefold increase in size of the mammalian telomerase RNAs relative to ciliate telomerase RNAs is due to the presence of an extra domain resembling a box H/ACA small nucleolar RNA (snoRNA). The human telomerase RNA (hTR) H/ACA domain is essential in vivo for hTR accumulation, hTR 3' end processing, and telomerase activity. By substituting the U64 box H/ACA snoRNA for the hTR H/ACA domain, we demonstrate that a heterologous snoRNA can function to promote chimeric RNA accumulation and 3' end processing but not telomerase activity. In addition, we show that maturation of full-length hTR and its assembly into active telomerase occur from an mRNA promoter-driven RNA polymerase II transcript but not from a U6 snRNA promoter-driven RNA polymerase III transcript. Finally, we show that a small percentage of hTR is associated with nucleoli. These results have implications for the biogenesis and structure of hTR and the human telomerase ribonucleoprotein complex. They also expand the structural and functional diversity of the box H/ACA snoRNA motif.
Collapse
|
43
|
Mitchell JR. The "Diana effect". There was no "Diana effect" on numbers of psychiatric emergencies. BMJ (CLINICAL RESEARCH ED.) 1998; 316:1751. [PMID: 9652939] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
|
44
|
Lipman BT, Collier BD, Carrera GF, Timins ME, Erickson SJ, Johnson JE, Mitchell JR, Hoffmann RG, Finger WA, Krasnow AZ, Hellman RS. Detection of osteomyelitis in the neuropathic foot: nuclear medicine, MRI and conventional radiography. Clin Nucl Med 1998; 23:77-82. [PMID: 9481493 DOI: 10.1097/00003072-199802000-00003] [Citation(s) in RCA: 73] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The diagnostic efficacy of (1) combined three-phase bone scintigraphy and In-111 labeled WBC scintigraphy (Bone/WBC), (2) MRI, and (3) conventional radiography in detecting osteomyelitis of the neuropathic foot was compared. Conventional radiography was comparable to MRI for detection of osteomyelitis. MRI best depicted the presence of osteomyelitis in the forefoot. Particularly in the setting of Charcot joints, Bone/WBC was more specific than conventional radiography or MRI.
Collapse
|
45
|
Mitchell JR, Jones C, Karlik SJ, Kennedy K, Lee DH, Rutt B, Fenster A. MR multispectral analysis of multiple sclerosis lesions. J Magn Reson Imaging 1997; 7:499-511. [PMID: 9170034 DOI: 10.1002/jmri.1880070309] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Although quantification of the lesion burden from serial MR examinations of patients with multiple sclerosis (MS) is a common technique to assess disease activity in clinical trials, pathologic change may occur within a lesion without a corresponding change in volume. Therefore, measures of lesion volume and composition may improve the sensitivity of detecting disease activity. A new technique has been developed that provides information about the intensity composition of MS lesions in standard spin-echo MR examinations. The new technique is based on the multispectral "feature space" intensity distributions of the lesions and normal tissues. Analysis of MR examinations of materials with known T1 and T2 times showed that feature space position from spin-echo examinations is largely determined from proton density (rho), T2, and the interecho delay. Information about intensity composition was obtained by reducing the multidimensional intensity distribution to one dimension while minimizing the loss of information. This technique was used to analyze eight lesions in standard spin-echo MR examinations of three patients with MS. Lesion distributions were compared between examinations by first calibrating the examinations based on the intensity distributions of cerebrospinal fluid (CSF), an internal reference tissue. Many of the lesion distributions had a distinctive peak at low intensity, corresponding to normal-appearing white matter (WM). Within the lesion distributions, increases in high intensity peaks generally were accompanied by reductions in the WM peak. Serial analysis of the lesion distributions revealed some dramatic fluctuations, even when lesion volume remained constant.
Collapse
|
46
|
Easa AM, Armstrong HJ, Mitchell JR, Hill SE, Harding SE, Taylor AJ. Maillard induced complexes of bovine serum albumin--a dilute solution study. Int J Biol Macromol 1996; 18:297-301. [PMID: 8739134 DOI: 10.1016/0141-8130(96)01090-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Association of bovine serum albumin (BSA) on heating in the presence and absence of 2% xylose has been studied using dynamic light scattering and sedimentation velocity. When 3% solutions of the protein alone are heated at 95 degrees C association products are formed with molar masses of approximately 2 x 10(6) g/mol, a value which is independent of the time of heating. These aggregates can be dissociated in solvents that disrupt non-covalent bonds. When the reducing sugar xylose is present there is a continuous change in the hydrodynamic properties with time. After 80 min a molar mass in excess of 7 x 10(6) g/mol is obtained. This increase in molar mass is attributed to additional non-disulphide linkages resulting from the Maillard reaction. Information about the gross conformation of the Maillard induced association products has been obtained from MHKS (Mark-Houwink-Kuhn-Sakarada) double logarithmic plots of D20,w and S20,w against molar mass. The values of the MHKS coefficients obtained are most consistent with a linear rod: i.e. the association is of an end-to-end type.
Collapse
|
47
|
Mitchell JR, Karlik SJ, Lee DH, Eliasziw M, Rice GP, Fenster A. Quantification of multiple sclerosis lesion volumes in 1.5 and 0.5 T anisotropically filtered and unfiltered MR exams. Med Phys 1996; 23:115-26. [PMID: 8700022 DOI: 10.1118/1.597689] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Recently, guidelines for the use of MRI in the monitoring of MS have recommended the use of imaging systems with mid-field (0.5-1.0 T) or high-field (greater than 1.0 T) strengths. Higher field strengths provide many advantages, including increased signal-to-noise ratios (SNR). SNR also may be increased by post-processing algorithms that reduce noise. In this paper we evaluate the impact on operator variability of (a) lesion quantification in high-field (1.5 T) versus mid-field (0.5 T) exams; and (b) an anisotropic diffusion filter algorithm that reduces image noise without blurring or moving object boundaries. Inter- and intra-operator reliability and variability were studied using repeated quantification of lesions in 1.5 and 0.5 T filtered and unfiltered MR exams of a MS patient. Results indicate that inter-operator variability in 1.5 T unfiltered exams was 0.34 cm3 and was significantly larger than that in 1.5 T filtered (0.27 cm3), 0.5 T unfiltered (0.26 cm3), and 0.5 T filtered (0.24 cm3) exams. Similarly, intra-operator variability in 1.5 T unfiltered exams was 0.23 cm3 and was significantly larger than that in 1.5 T filtered (0.19 cm3), 0.5 T unfiltered (0.19 cm3), and 0.5 T filtered (0.18 cm3) exams. In addition, the minimum significant change between two successive measurements of lesion volume by the same operator, was 0.64 cm3 in 1.5 T unfiltered exams, but 0.53 cm3 or less in other exams. For two different operators making successive measurements, the minimum significant change was 0.94 cm3 in 1.5 T unfiltered exams, but only 0.75 cm3 or less in other exams. Finally, the number of lesions to be monitored for an average change in volume at a given power and significance level was greater by 30%-60% for quantification in 1.5 T unfiltered exams. These results suggest that inter- and intra-operator variability are reduced by anisotropic filtering, and by quantification in 0.5 T exams. Reduced operator variabilities may result from higher detail signal-to-noise ratios (dSNRs) in 0.5 T and filtered exams.
Collapse
|
48
|
Mitchell JR, Karlik SJ, Lee DH, Eliasziw M, Rice GP, Fenster A. The variability of manual and computer assisted quantification of multiple sclerosis lesion volumes. Med Phys 1996; 23:85-97. [PMID: 8700036 DOI: 10.1118/1.597685] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
The high resolution and excellent soft tissue contrast of Magnetic Resonance Imaging (MRI) have enabled direct, noninvasive visualization of Multiple Sclerosis (MS) lesions in vivo. This has allowed the quantification of changes in the appearance of lesions in MR exams to be used as a measure of disease state. Nevertheless, accurate quantification techniques are subject to inter- and intra-operator variability, which may hinder monitoring of disease progression. We have developed a computer program to assist an experienced operator in the quantification of MS lesions in standard spin-echo MR exams. The accuracy of assisted and manual quantification under known conditions was studied using exams of a test phantom, while inter- and intra-operator reliability and variability were studied using exams of a MS patient. Results from the phantom study show that accuracy is improved by assisted quantification. The patient exam results indicate that assisted quantification reduced inter-operator variability from 0.34 to 0.17 cm3, and reduced intra-operator variability from 0.23 to 0.15 cm3. In addition, the minimum significant change between two successive measurements of lesion volume by the same operator was 0.64 cm3 for manual quantification and 0.42 cm3 for assisted quantification. For two different operators making successive measurements, the minimum significant change was 0.94 cm3 for manual quantification, but only 0.47 cm3 for assisted quantification. Finally, the number of lesions to be monitored for an average change in volume at a given power and significance level was reduced by a factor of 2-4 by assisted quantification. These results suggest that assisted quantification may have practical applications in clinical trials, especially those that are large, multicenter, or extended over time, and therefore require lesion measurements by one or more operators.
Collapse
|
49
|
Sousa IM, Mitchell JR, Ledward DA, Hill SE, da Costa ML. Differential scanning calorimetry of lupin and soy proteins. Eur Food Res Technol 1995; 201:566-9. [PMID: 8585334 DOI: 10.1007/bf01201587] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Differential scanning calorimetry (DSC) was used to study the 7S and 11S globulin fractions extracted from lupin seed (Lupinus luteus) flour. In agreement with previous work on other lupin species, the isolate showed three denaturation peaks compared to the two observed with soy. By comparison with the isolated globulin fractions, the denaturation peaks at the two higher temperatures in the lupin isolate were assigned to the 11S and 7S globulins. The denaturation temperature of the lupin 7S globulin was about 10 K higher than that for the corresponding soy globulin, whereas the values for the 11S globulin were similar. All globulins displayed increasing thermal stability with decreasing moisture contents. Possible reasons for the differences in behaviour of soy and lupin protein isolates are discussed.
Collapse
|
50
|
Mitchell JR, Johnson JE, Collier BD, Gould JS. Stress fracture of the tibia following extensive hindfoot and ankle arthrodesis: a report of three cases. Foot Ankle Int 1995; 16:445-8. [PMID: 7550961 DOI: 10.1177/107110079501600713] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
|