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Narayanan A, Russell MD, Sundararaman S, Shankar KK, Artman B. Takotsubo cardiomyopathy following electroconvulsive therapy: an increasingly recognised phenomenon. BMJ Case Rep 2014; 2014:bcr-2014-206816. [PMID: 25425252 DOI: 10.1136/bcr-2014-206816] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Treatment of patients with severe depressive illnesses requiring electroconvulsive therapy (ECT) is challenging. This is compounded by the presence of physical comorbidities and potential complications. We report the case of a patient, on long-term bisoprolol, who developed acute epigastric pain and dyspnoea shortly after receiving ECT for treatment-refractory depression. An ECG showed new-onset ischaemic changes and a troponin-I level was elevated at 12 h. A diagnosis of Takotsubo cardiomyopathy was reached following angiography, which demonstrated left ventricular hypokinesia in the absence of coronary artery disease. With supportive treatment the patient made a good recovery. This report highlights the risk of developing Takotsubo cardiomyopathy following ECT despite β-adrenergic receptor blockade, and adds to a growing number of cases reporting this complication. Clinicians involved in the care of patients undergoing ECT must be aware of this complication and should consider Takotsubo cardiomyopathy in patients who develop atypical chest pain after ECT.
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Affiliation(s)
- A Narayanan
- Lister Hospital, Stevenage, Hertfordshire, UK
| | - M D Russell
- Lister Hospital, Stevenage, Hertfordshire, UK
| | | | - K K Shankar
- Lister Hospital, Stevenage, Hertfordshire, UK
| | - B Artman
- Lister Hospital, Stevenage, Hertfordshire, UK
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Jarad FD, Moss BW, Youngson CC, Russell MD. The effect of enamel porcelain thickness on color and the ability of a shade guide to prescribe chroma. Dent Mater 2007; 23:454-60. [PMID: 16631924 DOI: 10.1016/j.dental.2006.03.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2005] [Revised: 12/06/2005] [Accepted: 03/08/2006] [Indexed: 11/24/2022]
Abstract
OBJECTIVE To test the null hypothesis that there is no color change when enamel porcelain thickness is changed and to evaluate the ability of a shade guide to prescribe chroma. METHODS Three shades (3M1, 3M2 and 3M3) were selected from a Vitapan 3D master shade guide. Five disk specimens were prepared for each shade, consisting of three layers (opacious dentin, dentin and enamel) at thicknesses of 0.6, 0.8 and 0.6mm, respectively. The color of each disk was measured using a spectrophotometer. Enamel porcelain was reduced in thickness to 0.3mm and porcelain disks were remeasured. RESULTS Reducing the enamel thickness of porcelain disk specimens significantly increased L) (p<0.05), b*, metric chroma and hue angle (p<0.001). For the three shades studied (3M1, 3M2 and 3M3) L* values were not significantly different (p>0.05) and chroma increased for 3M1 with the lowest chroma to 3M3 with the highest chroma, which is in line with the shade guide specifications. Although statistically significant (p<0.001) changes in hue angle between the three shades were small (less than 3 degrees overall). The difference in chroma between the three shades 3M1, 3M2 and 3M3 was greatest for the thin enamel layer than the thick enamel layer. SIGNIFICANCE A change in enamel thickness from 0.6 to 0.3mm resulted in a three-unit change in L* and metric chroma and a 4 degrees change in hue angle. A change in enamel porcelain thickness will have a greater effect on higher chromatic shades than those with lower chroma. The ability of the shade guide to prescribe chroma was demonstrated but this could be offset by an anomalous enamel thickness.
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Affiliation(s)
- F D Jarad
- Restorative Dentistry, Unit of Restorative Dentistry, School of Dental Studies, Liverpool University Dental Hospital, Pembroke Place, Liverpool, L3 5PS, UK.
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Jarad FD, Russell MD, Moss BW. The use of digital imaging for colour matching and communication in restorative dentistry. Br Dent J 2005; 199:43-9; discussion 33. [PMID: 16003426 DOI: 10.1038/sj.bdj.4812559] [Citation(s) in RCA: 98] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2002] [Accepted: 11/14/2003] [Indexed: 11/09/2022]
Abstract
OBJECTIVE To develop a shade matching method based on digital imaging and to compare observers' ability using this method with the conventional one set against a spectrophotometric 'gold standard'. METHODS Two Vita Lumin shade guides were used in this study, nine shades being selected from the first Vita Lumin shade guide, A2, A3, A3.5, B2, B3, B4, C1, C2 and C3. A second shade guide was used to match the selected shades. A Nikon Coolpix 990 digital camera with Nikon SB21B ring flash was used to record the digital images of the shade tabs of the two shade guides and the images were processed using Adobe Photoshop software. A total of 27 samples (three replicates of each shade of the nine tabs selected) were matched with a digital shade guide prepared from the digital images of the second shade guide by 10 observers on a computer screen (computerised matching method). The 10 observers also matched the same shade tabs using the conventional matching method simulated in a phantom head. In addition, colour values were obtained from the digital images using Adobe Photoshop and quantified according to an internationally recognised scale as CIELAB colour values, L*,a*,b*. The relationship of the digitally derived CIELAB values to the CIELAB values obtained using a reflectance spectrophotometer was investigated. RESULTS The cross tabulation statistical analysis showed a statistically significant difference (p<0.001) between the conventional method and the computer method with a 43% and 61.1% correct match respectively. There was also a statistically significant difference between observers in both methods (p<0.001 and p<0.04 for the conventional and computer methods respectively). A statistically significant high correlation of the CIELAB colour values were found between both colour measurement methods (p<0.001). CONCLUSION The observers' shade matching performance was significantly better with the computer method compared with the conventional one. There was a large variation in the observers' matching ability. The digital camera can be used as a means of colour measurements in the dental clinic.
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Affiliation(s)
- F D Jarad
- Liverpool University Dental Hospital, Pembroke Place, Liverpool, L3 5PS.
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Ibrahim SK, Minnis ST, Barker AD, Russell MD, Haydock PP, Evans K, Grove IG, Woods SR, Wilcox A. Evaluation of PCR, IEF and ELISA techniques for the detection and identification of potato cyst nematodes from field soil samples in England and Wales. Pest Manag Sci 2001; 57:1068-1074. [PMID: 11721525 DOI: 10.1002/ps.397] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Effective management of potato cyst nematodes (PCNs) requires simple, rapid and accurate identification and quantification of field populations. Soil samples from a survey of 484 fields in potato rotations in England and Wales were used to compare the identification and quantification of PCNs using IEF, PCR, ELISA and bait plant tests. The cyst counts and bait plant test revealed that 64.3% of field samples contained PCNs. Bait plant tests increased the detection rate of PCNs in field samples by 4-6.4%. This means that some infestations are cryptic and would not normally be detected by standard counts. IEF, PCR and ELISA methods distinguished between Globodera rostochiensis and G pallida and were able to register mixed populations; however they were not in full agreement. All methods suggested that G pallida is the dominant species in the field samples tested. The PCR results indicated that 66% of field samples contained pure G pallida, 8% contained pure G rostochiensis and 26% contained mixtures of the two species. Estimates of the relative process times taken per sample in the PCR, IEF and ELISA techniques are given.
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Affiliation(s)
- S K Ibrahim
- Crop and Environment Research Centre, Harper Adams University College, Newport, Shropshire TF10 8NB, UK.
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Abstract
This case was first reported by one of the authors in 1987, subsequent to the patient being treated using a combination of a hinge and split pin sectional denture. The same patient attended for review some 14 years later for assessment of this denture at which stage a replacement was made.
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Affiliation(s)
- C W Barclay
- School of Dentistry, The University of Birmingham.
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Abstract
It has been observed that teeth become lighter when they are dried. The present study was designed to quantify these changes and the time taken for tooth colour to return to normal. The colour of an upper central incisor in each of seven subjects was measured using a reflectance spectrophotometer before and after application of a rubber dam and, in another seven subjects before and after taking a polyvinylsiloxane impression. There were statistically significant changes in the L*, a* and b* values following rubber dam application and in the L* value following impression taking. The results demonstrate that teeth become brighter and less colour saturated after rubber dam application and brighter after impression taking. The original values were regained after 30 min.
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Affiliation(s)
- M D Russell
- Division of Restorative Dentistry, School of Clinical Dentistry, The Queen's University of Belfast, Northern Ireland.
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Abstract
OBJECTIVES Glass-ionomer luting cements are supplied in two forms, as loose powder and liquid to be hand-mixed (HM) or pre-proportioned in a capsule to be mechanically mixed (MM). This study was to determine if post retention in pull-out tests was affected by the method of mixing the cement. METHODS Two hundred stainless steel posts of diameter 1.75 mm were cemented within post-channels prepared in stainless steel cylinders using two hand-mixed cements FJL and KCL (Fuji I Luting Cement and Ketac-Cem Luting Cement) and two capsulated cements FJC and KCM (Fuji Cap I and Ketac-Cem Maxicap). Three groups of test specimens were prepared. In Group I each cement was mixed as recommended by the manufacturer, Group II cements were placed within a capsule and mechanically mixed and in Group III cements were removed from the capsule and mixed by hand. Specimens were stored for 1 h at 37 degrees C and 100% humidity prior to post pull-out tests at a crosshead speed of 10 mm min-1. The maximum loads at failure were subjected to Weibull analysis and Mann-Whitney tests to determine probabilities of survival and significant differences between the groups. RESULTS Significant differences (P < 0.05) were found between all pairs of cements tested except KCM(MM) vs FJL(HM), FJL(MM) vs KCL(HM), KCL(MM), vs KCL(HM), FJC(HM) vs FJC(MM), KCL(MM) vs FJL(MM). CONCLUSIONS The capsulated cements as supplied by the manufacturers are preferable to the equivalent hand-mixed formulations, as they give higher probabilities of survival when subjected to a given load. Both capsulated and hand-mixed formulations of Fuji had higher probabilities of survival compared to the corresponding Ketac cements. The probability of post survival can be altered by the method of mixing the cement.
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Affiliation(s)
- C A Mitchell
- Department of Restorative Dentistry, Queen's University of Belfast, UK
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Russell MD, Masood M, Cunningham L. The behaviour of post-retained core materials supported by coronal tooth structure in vitro. Int Endod J 1997; 30:408-12. [PMID: 9588981 DOI: 10.1046/j.1365-2591.1997.00108.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
This study was designed to investigate the effect of retaining coronal tooth substance on the performance of post-retained core materials, and to compare the fracture resistance of the system with an intact tooth prepared to similar dimensions. Ten teeth restored with post-retained silver amalgam, and 10 teeth restored with silver-glass cermet, all with a retained single wall of coronal tooth substance, were compared with 10 unrestored teeth prepared to similar dimensions when subjected to a shearing load. The results showed no statistically significant difference between the unrestored teeth and those restored with a silver-glass cermet. Whilst the teeth restored with silver amalgam had a significantly higher fracture resistance (P > 0.01) there was greater tendency to root fracture.
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Affiliation(s)
- M D Russell
- Division of Restorative Dentistry, School of Clinical Dentistry, Queen's University of Belfast, UK
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Mauceri T, Biggs PJ, Beatty J, Doppke K, Gall K, Hong L, Leong J, Lo YC, Rosenthal SR, Russell MD. A method for predicting the variation of the depth of maximum dose in shaped electron fields. Med Phys 1996; 23:695-7. [PMID: 8724742 DOI: 10.1118/1.597716] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Affiliation(s)
- T Mauceri
- Department of Radiation Oncology, Massachusetts General Hospital, Harvard Medical School, Boston 02114, USA
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Abstract
OBJECTIVE This paper investigates the efficacy of practical participation as a vehicle for conveying knowledge of the subject of dental occlusion. METHODS A fourth-year class of students was divided into two groups: one had benefited from a series of practicals focusing on the re-organized approach to occlusion, and the other had attended routine clinical sessions in conservative dentistry. Both had attended the same course of four lectures. Their knowledge was tested by means of a short answer question paper. RESULTS The group attending the focused practicals out-performed the control group at the 0.01 level of significance. CONCLUSION Practical participation would appear to enhance students' understanding of the subject of dental occlusion.
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Affiliation(s)
- M D Russell
- School of Clinical Dentistry, Queen's University of Belfast, UK
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Russell MD. Cross-infection policy. Br Dent J 1994; 176:411. [PMID: 8018427 DOI: 10.1038/sj.bdj.4808466] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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Russell MD. Problems associated with restoration of dentitions after orthodontic treatment using anterior tooth space. Eur J Prosthodont Restor Dent 1992; 1:25-9. [PMID: 1291021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Three case reports are presented to illustrate some problems associated with restoration of dentitions following orthodontic treatment using anterior tooth space. These include the projecting premaxilla, conversion of lateral incisors to resemble central incisors and excess residual space.
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Affiliation(s)
- M D Russell
- School of Dentistry, Royal Victoria Hospital, Belfast, Northern Ireland
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Burrell CJ, Russell MD, Stewart J. Evaluation of accuracy of the wash impression technique to rebase and replace the resilient part of a soft-lined denture. J Prosthet Dent 1991; 65:408-13. [PMID: 2056460 DOI: 10.1016/0022-3913(91)90233-m] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The dimensional inaccuracies that might be introduced during a wash impression technique within a heat-cured acrylic resin tray lined with a silicone resilient denture base material were investigated with the use of an electronic digitizer. Casts were poured from impressions of a machined metal die using a light- and heavy-bodied addition silicone in the soft-lined tray and compared with casts poured from impressions made in a hard-based tray and with the master die itself. The dimensions of the casts poured from the heavy-bodied impression in the soft-lined trays were significantly different from those poured from impressions in the hard-based tray when compared with the metal die. Those produced from the light-bodied material showed no statistically significant dimensional difference.
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Affiliation(s)
- C J Burrell
- Oral Surgery Department, York District Hospital, England
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Abstract
A few patients undergoing pelvic irradiation present with a prosthetic hip. The presence of this metal object often interferes with the lateral treatment fields if a four-field box irradiation technique is used. Measurements of the effect such a prosthesis may have on the dose delivered to the pelvis for beams of 60Co gamma rays and 10 MV and 25 MV X-rays, as a function of field size and depth have been made. The results show a strong variation in the dose behind the prosthesis depending on the position of the measurement, with little or no increase through the center of the head or ball, but a sharp drop either around its circumference or along the stem of the prosthesis. Measurements made with ionization chambers through the head of the prosthesis indicate an average dose decrease of approximately 2% for 25 MV X rays and average increases of approximately 2% for 10 MV X rays and 5% for 60Co. There is little variation with field size and depth except close to the prosthesis, at 25 MV. Measurements also indicate an increase in dose close to the upstream surface of the prosthesis at all energies, but in the downstream direction, only the data at 25 MV shows an increase.
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Affiliation(s)
- P J Biggs
- Department of Radiation Medicine, Massachusetts General Hospital, Boston 02114
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Abstract
Gross and microscopic examination of the Krapina Neanderthal dental remains reveals the presence of artificial grooves along the cemento-enamel junction of 14 teeth representing ten different individuals. The grooves display distinct morphological features including their consistent location (primarily on the mesial and/or distal root walls), their troughlike appearance, striations and/or polishing in the channel, and the ridges of reactive cementum bordering the groove. These grooves occur only on erupted, permanent teeth, and except for a single occurrence on a lower I2, all are located on mandibular or maxillary P4-M3. The morphological nature of the grooves is distinct and has been used to distinguish these grooves from root caries and other pathological or natural causes. Based on the close resemblance between artificial grooves at Krapina and those which have been attributed to toothpick use in other fossil and recent populations, we argue the Krapina Neanderthals were habitually probing the interproximal dental spaces with tools.
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Affiliation(s)
- D W Frayer
- Department of Anthropology, University of Kansas, Lawrence 66045
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Abstract
Orthodeoxia--arterial desaturation accentuated by the upright position and improved by recumbency--has been described earlier with true pulmonary vascular shunts and intracardiac shunts. This phenomenon has been described in some parenchymal lung diseases, but has not been reported with interstitial fibrosis. We describe 2 patients with predominantly basal interstitial fibrosis, disabling dyspnea, and severe hypoxemia who demonstrated this positional oxygenation change. Large or surgically correctable arteriovenous malformations (AVM), or intracardiac shunts, were not demonstrated in either patient. This finding has important implications for oxygen prescription and the explanation of positional dyspnea.
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Abstract
It has often been reported that the Krapina Neandertal remains bear incised linear striations which appear to be cutmarks. Here, the plausibility of the striations as cutmarks is tested by comparing them to Mousterian butchery marks on large fauna and to cutmarks on modern human skeletons known to have been defleshed with stone tools. The anatomical location, gross appearance, and frequency of occurrence of the striations on the Krapina material do not resemble Mousterian butchery marks on reindeer. The Krapina striations do closely match authenticated cutmarks on 22 modern human skeletons defleshed with stone tools after partial decomposition, preparatory to secondary burial. Data are presented supporting the hypothesis that the striations on the Krapina Neandertal remains are consistent with postmortem processing of corpses with stone tools, probably in preparation for burial of cleaned bones.
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Abstract
The fragmentary condition of the Krapina Neandertal remains has been offered as one line of evidence for the hypothesis that these hominids were the victims of cannibals seeking marrow and brains. Two other hypotheses regarding the causes of the framentation have been raised: a substantial portion of the breakage in the Krapina collection is attributable to excavation damage; and the rest of the breakage is attributable to sedimentary pressure and to natural rock falls that occurred during the site's prehistory. The purpose of this paper is report on tests of these three hypotheses concerning the cause of breakage in the Krapina material. Microscopic inspection of all Krapina hominid specimens showed that 23% of the material was inadvertantly broken during excavation or during quarrying that took place at the end of the last century. The morphology of the prehistoric breakage is inconsistent with the cannibalism hypothesis and supports the hypothesis that prehistoric breakage was caused by sedimentary pressure and/or roof falls.
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Russell MD. The role of provisional restorations. Dent Update 1986; 13:425-6, 428, 430 passim. [PMID: 3468021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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Russell MD. The conversion crown revisited. Restorative Dent 1986; 2:92-3, 95. [PMID: 3534976] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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Russell MD, Torrington KG, Tenholder MF. A ten-year experience with fiberoptic bronchoscopy for mycobacterial isolation. Impact of the Bactec system. Am Rev Respir Dis 1986; 133:1069-71. [PMID: 3087251 DOI: 10.1164/arrd.1986.133.6.1069] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
From January 1974 to December 1983, positive mycobacterial isolates from all sources were reviewed to determine the impact of fiberoptic bronchoscopy (FB) on retrieval and identification of these organisms. There were 112 patients with positive cultures obtained during FB, 25 with Mycobacterium tuberculosis and 87 with mycobacteria other than tuberculosis (MOTT). We reviewed the results of prebronchoscopy and postbronchoscopy sputum specimens, bronchial washings, brushings, and transbronchial biopsy to determine the yield from each specimen in patients with M. tuberculosis. The bronchial washings provided positive cultures in 24 of 25 and were exclusively positive in 10 of 25 (40%). We also reviewed the clinical presentation, chest roentgenogram, bronchoscopy findings, and culture data for the 87 patients with MOTT isolated. The isolation of MOTT from bronchoscopy specimens increased throughout the study, most notably with the introduction of a rapid radiometric method (the Bactec system) for the recovery of mycobacteria to our laboratory in June 1983. Active disease could be established in only 13 of 87 cases (15%). Our findings confirm the sensitivity of Bactec in the isolation of MOTT from bronchoscopic specimens. The Bactec system, on the other hand, does not differentiate saprophytic colonization from clinical disease. To avoid expensive, time-consuming biochemical identification necessary to evaluate these MOTT isolates, careful selection of patients prior to obtaining mycobacterial cultures during FB is a critical factor.
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Abstract
An examination of the surface morphology of the juvenile Neandertal calvaria, Engis 2, has resulted in the discovery of several series of incised striations. The purpose of this paper is to describe and discuss these striations. A preliminary interpretation of at least some of the striations as cutmarks, made at or near the time of the child's death, is offered.
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Davenport JC, Russell MD. Nasal vestibular stents. Quintessence Dent Technol 1986; 10:93-7. [PMID: 3457407] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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Abstract
The ability to control thermal drifts is essential in operating a calorimeter. We investigated a thermal enclosure, which envelops the calorimeter with temperature-regulated air, thus thermally isolating the calorimeter from the room. The desired temperature in the enclosure is controlled by a control circuit and a thermoelectric device, which works as a Peltier effect heat pump. In this report, the details of the enclosure design and construction are presented with actual performance evaluations.
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Russell MD. Metal provisional crowns and bridges. Restorative Dent 1985; 1:100-2. [PMID: 3898245] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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28
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Abstract
The quality of portal films taken at megavoltage energies is frequently poor, despite the use of various techniques such as lead screens to improve the image. When critical structures, such as the spinal cord, are to be blocked out of the treatment field, it is frequently difficult to determine whether the block is correctly placed. To solve this problem, a diagnostic X ray source has been mounted on the side of a 10 MV linear accelerator to provide accurate verification of patient positioning and location of shielding blocks. The coincidence between the mechanical, 10 MV and diagnostic X ray isocenters is about 1 mm. The system has been designed so that procedures to monitor this coincidence, and adjustment procedures to maintain it, are easily performed.
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Abstract
The presence of secondary electrons in photon beams of 60Co and 4, 8, 10, 15 and 25 MV x-rays has been studied by measuring surface charge using thin window ionisation chambers. Measurements have been made for square fields from 4 X 4 cm2 to 35 X 35 cm2 for locations from the collimator head to a distance of 4 m from the target. In addition, measurements have been made for rectangular fields at 10 MV and 25 MV for fields of equivalent area from 5 X 5 cm2 to 25 X 25 cm2. By eliminating the inverse square effect, the presence of contaminants from the head and the effect of build-up in air are clearly seen and well separated. Comparison between the curves at different energies indicates an increasing effect of contamination from the head with energy and a decreasing effect of electron production in air with increasing energy.
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Abstract
It has been suggested that masticatory efficiency is directly related to the area of the occlusal surfaces that make contact. However, little work has been carried out to determine if occlusal wear increases the area of contact, and controversy exists as to whether this would be an advantage. Using a wax registration method, occlusal contact area was measured in a group of individuals with either local or generalized wear, before and after treatment. The changes in occlusal contact area were statistically significant for the group exhibiting generalized wear but not for the group exhibiting localized war.
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Allen LL, Bridges PS, Evon DL, Rosenberg KR, Russell MD, Schepartz LA, Vitzthum VJ, Wolpoff MH. Demography and Human Origins. American Anthropologist 1982. [DOI: 10.1525/aa.1982.84.4.02a00140] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Abstract
The employment of a 10 MV X ray beam for treatment of head and neck tumors has been investigated. A 1.2 cm thick beam spoiler positioned 7 cm from the patient surface was used to achieve adequate dose to the superficial region. This technique provides at least 90% depth dose at 0.5 cm depth, which is clinically required for the treatment. For departments able to acquire only one megavoltage machine, the technique can provide an option to treat adequately both shallow as well as deep-seated tumors by choosing a high megavoltage machine; a low megavoltage machine cannot provide an equivalent option to treat deep-seated tumors.
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Abstract
Tissue phantom ratios (TPR), based on a normalization depth of 5 cm, have been measured in water for field sizes from 5 x 5 cm2 to approximately 40 x 40 cm2 and for depths from 1 to 40 cm for a Varian Clinac 4/100. These TPR's have been compared with those calculated from percent depth doses measured at the same time, and the two sets of data generally agree to better than 1%, with an average ratio of measured to calculated TPR of 0.999 +/- 0.013. Beam profiles have been measured for open and wedged fields, with particular concern for the often observed "horns," or the increase in dose at the corners of the field. The maximum dose at a depth of 1 cm, along the diagonal of the field for this machine, is approximately 5% higher than at the same depth on the central axis, whereas along the principal plane the maximum dose is only about 3% higher.
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Abstract
One of the most reasonable hypotheses regarding the functional significance of the browridge is that the supraorbital torus forms in response to masticatory stress during development. Oyen, Walker, and Rice (1979) have recently proposed a model that tests this hypothesis: if browridges are functionally related to masticatory stresses on the cranial vault, then changes in the biomechanics of the masticatory system ought to be reflected by changes in the browridge. To test their model they attempted to relate biomechanical discontinuities resulting from tooth eruption to episodes of bone deposition on the supraorbital tori of a developmental series of dry Papio crania. This paper reports on a parallel test of the model on a cross-sectional sample of Australian Aboriginal juvenile crania. This sample showed no relation between tooth eruption and the supraorbital surface morphology thought to be indicative of active bone deposition. It is also demonstrated that no significant relationship between tooth eruption and episodes of bone deposition is shown by the Papio sample. It is concluded that the use of small cross-sectional samples of dry crania does not provide a valid test of the model.
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Abstract
No evidence supports the interpretation of malocclusion in the LH-14 right P3. The pattern of anterior cutting shown in the younger laetolil specimens has its analogue in the deciduous dentitions of Pongo.
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