bluuebunny/crossref_metadata_2025 huggingface dataset:
Adverse outcomes following emergency department discharge of patients with possible acute coronary syndrome
Authors: Loten Conrad , Isbister Geoffrey , Jamcotchian Melissa , Hullick Carolyn , MacElduff Patrick , Attia John , Marley John
Published: November 2009

Objective:  To determine the proportion of adverse events in patients discharged after ED assessment for possible acute coronary syndrome.

Methods:  Prospective observational cohort study enrolling consecutive patients presenting with symptoms suggestive of coronary syndrome. Main outcome was the proportion of adverse coronary events (defined a priori) within 30 days.

Results:  Of 2627 patients, 1819 (69%) were discharged without a diagnosis of coronary syndrome and 808 (31%) were admitted for further investigation and treatment. Of these, 385 (14.7%) were given a final diagnosis of acute coronary syndrome. On 30 day follow up, 18 of the discharged patients were diagnosed with acute coronary syndrome (0.7%; 95% confidence intervals [CI] 0.4–1.1%), 10 with unstable angina (0.4%; 95% CI 0.2–0.7%) and 8 with non‐ST elevation myocardial infarction (0.3%; 95% CI 0.2–0.6%). There were no cases of ST elevation infarction or death. The sensitivity for diagnosis of acute coronary syndromes was 95.5% (95% CI 92.9–97.3%). Average length of stay was 7 h for discharged patients. Forty‐six per cent of patients with diabetes and 47% with a past history of coronary disease were discharged. Subsequent outpatient stress testing was performed in 13.6%.

Conclusions:  In a large Australian ED, less than 1% of patients presenting with symptoms suggestive of coronary syndrome were discharged and subsequently had a 30 day adverse event. Reducing this proportion by admitting patients with traditional risk factors would markedly increase hospital workload. Opportunities exist to improve both the safety and efficiency of chest pain assessment in the ED.
Consequences of an unrecognized measles exposure in an emergency department
Authors: Bowen Asha C , Ferson Mark J , Palasanthiran Pamela
Published: November 2009

A recent measles case in a paediatric hospital ED resulted in 111 individuals (patients, family members and health‐care workers) potentially being exposed to measles. This report documents the efforts taken to contact trace and provide best practice care for all those exposed to the index case. It also provides a snapshot of community prevalence information on immunity to measles. One hundred per cent of contacted children (n= 24) eligible for vaccination were immunized, whereas 96% of adults surveyed or tested (n= 44) had assumed or proven immunity. However, six infants aged between 6 and 9 months were exposed and might have been a sufficiently large reservoir to facilitate the ongoing spread of measles in the community, if contact tracing and preventative measures had not occurred. This scenario also highlights the need to consider measles in the ED, particularly among travellers, with urgent isolation of suspected cases in the ED according to guidelines discussed.
Queensland Emergency Medical System: A structural and organizational model for the emergency medical system in Australia
Authors: FitzGerald Gerry , Tippett Vivienne , Schuetz Michael , Clark Michele , Tighe Trevor , Gillard Noel , Higgins Jim , Elcock Mark
Published: November 2009

Objective: The emergency medical system (EMS) can be defined as a comprehensive, coordinated and integrated system of care for patients suffering acute illness and injury. The aim of the present paper is to describe the evolution of the Queensland Emergency Medical System (QEMS) and to recommend a strategic national approach to EMS development.

Methods: Following the formation of the Queensland Ambulance Service in 1991, a state EMS committee was formed. This committee led the development and approval of the cross portfolio QEMS policy framework that has resulted in dynamic policy development, system monitoring and evaluation. This framework is led by the Queensland Emergency Medical Services Advisory Committee.

Results: There has been considerable progress in the development of all aspects of the EMS in Queensland. These developments have derived from the improved coordination and leadership that QEMS provides and has resulted in widespread satisfaction by both patients and stakeholders.

Conclusions: The strategic approach outlined in the present paper offers a model for EMS arrangements throughout Australia. We propose that the Council of Australian Governments should require each state and Territory to maintain an EMS committee. These state EMS committees should have a broad portfolio of responsibilities. They should provide leadership and direction to the development of the EMS and ensure coordination and quality of outcomes. A national EMS committee with broad representation and broad scope should be established to coordinate the national development of Australia's EMS.
Fractured Penis: Diagnosis and Management (CME)
Authors: Al-Shaiji Tariq F. , Amann Justin , Brock Gerald B.
Published: November 2009

Introduction

Penile fracture is a well-recognized clinical entity. It is relatively uncommon and is considered a urological emergency. Its management has been a subject of controversy.

Aim

In this article, we will review contemporary knowledge of the epidemiology, pathophysiology, evaluation, and evolving management strategies of penile fracture.

Methods

A case report was discussed followed by an English-language Medline review.

Main Outcome Measure

Review of the available literature to establish best-practice management.

Results

The injury is defined as the traumatic rupture of the corpus cavernosum secondary to a blunt trauma of the erect penis. The condition is underreported. The commonest causes were coital injuries and penile manipulation. The diagnosis was usually fairly straightforward because of the stereotypical clinical presentation. Associated injuries included urethral rupture. Imaging was helpful in selected cases. Conservative measures were associated with increased complications. Most authors advocated early surgical repair. False explorations have been reported.

Conclusions

Penile fracture is a clinical diagnosis. The ideal management has evolved and remains largely surgical. Preoperative imaging should not delay surgical repair.
Epilepsy in the elderly
Authors: Leppik Ilo E. , Birnbaum Angela K.
Published: November 2009

The elderly, often defined as those 65 years or older, are the most rapidly growing segment of the population, and onset of epilepsy is higher in this age group than in any other. This paper reviews recent developments, including a new proposed definition of epilepsy, a transgenic mouse model of Alzheimer's disease that exhibits complex partial seizures, evidence that the highest incidence of epilepsy may occur after admission to a nursing home, a challenge to the vitamin D hypothesis of osteoporosis associated with antiepileptic drugs (AEDs), evidence that the genetic complement of hepatic isoenzymes is more predictive of metabolic rate than age, and data showing that there is considerable variability in serum levels of AEDs in many nursing home residents during constant dosing conditions.
Viral colonization in intubated patients: initial pathogen pattern and follow‐up
Authors: Hauptmeier Barbara Monika , Borg Irmgard , Rohde Gernot , Anders Agnes , Kronsbein Juliane , Gatermann Sören , Bufe Albrecht , Blum Torsten , Schultze‐Werninghaus Gerhard , Bauer Torsten Thomas
Published: November 2009

Introduction:  Colonization of the lower respiratory tract is an independent risk factor for ventilator‐associated pneumonia. Little is known about the frequency of viral colonization on intubation and during mechanical ventilation.

Methods:  Overall, 65 eligible intubated patients with no initial signs of pulmonary infection were studied over a period of up to 7 days. Tracheobronchial aspirates were taken: (i) within 48 h after intubation; and (ii) when clinical signs of nosocomial tracheobronchitis were present, before extubation, or after 7 days. Presence of respiratory viruses was investigated using quantitative polymerase chain reaction.

Results:  Patients were 67 ± 11 years old and had been in hospital for 5.1 ± 8.4 days when intubated (major cause for intubation: cardio‐pulmonary resuscitation 25/65, 38%). The average Acute Physiology and Chronic Evaluation II score was 27.3 ± 4.9. Microbiology detected Candida spp. (17/65; 26%) and Staphylococcus aureus (methicillin sensitive: 11/65; 17%; methicillin resistant: 3/65; 5%) and only few respiratory viruses (4/65, 6%). Thirty‐eight percent of the samples (25/65) were sterile. At the given endpoints, 27/65 (42%) patients were available for follow‐up and only one aspirate became positive for respiratory syncytial virus (RSV).

Conclusions:  After endotracheal intubation, fungi, but not viruses were most frequently isolated. Only one patient acquired RSV, therefore colonization with respiratory viruses does not seem to play a major role early after intubation.

Please cite this paper as: Hauptmeier BM, Borg I, Rohde G, Anders A, Kronsbein J, Gatermann S, Bufe A, Blum T, Schultze‐Werninghaus G and Bauer TT. Viral colonization in intubated patients: initial pathogen pattern and follow‐up. The Clinical Respiratory Journal 2010; 4: 139–146.
The economics of transit oil and gas pipelines: a review of the fundamentals
Authors: Omonbude Ekpen J.
Published: November 2009

The growing relevance of transit oil and gas pipelines is reflected in the general anticipation of an increase in their construction in the future because of factors such as the increasing discoveries of reserves in remote and land‐locked locations, the depletion of reserves close to established markets, and improvements in cost‐effective technological methods of exploration and production in previously uneconomic reserves. Recent disputes between parties to transit pipeline agreements demonstrate, in addition to other problems, the relevance of a fundamental analysis of the workings of oil and gas pipelines in economics. The objective of this paper therefore is to provide a fundamental framework for understanding and analysing transit oil and gas pipelines. The paper finds that the concept of economic rent, natural monopoly and basic cost concepts clearly explain the rationale behind the imposition of a transit fee, although they do not sufficiently define how they are determined.
Transportation demand for petroleum products in Indonesia: a time series analysis
Authors: Sa'ad Suleiman
Published: November 2009

This paper used annual time series data for the period 1973 to 2007 in two econometric techniques [the structural time series model (STSM) and unrestricted error correction model (UECM)] developed to estimate petroleum products (gasoline and diesel) and demand functions for the transportation sector of Indonesia and make a forecast of per capita consumption of the total products until the year 2030 under three scenarios. The results from both models revealed that the demand for petroleum products are price inelastic, with an estimated long‐run price elasticity of −0.19 in the STSM and −0.16 in the UECM. However, total petroleum is income elastic in the long run with a long‐run income elasticity of 0.97 under the STSM and 0.88 in the UECM. The estimated demand functions are used to construct a projection of future transportation demand for petroleum products until 2030 under three alternative scenarios: business as usual, low case scenario and high case scenario. The results of this exercise suggests that by 2030, the demand for total petroleum products per capita for Indonesia will increase to about 0.498 toe in the STSM and 0.476 toe in the UECM under the baseline scenario, 0.197 toe in the STSM and 0.186 toe in the UECM under low case scenario and finally, 0.976 toe in the STSM and 0.886 toe under high case scenario.
Cone dystrophy with supernormal rod response – case report
Authors: VARSANYI B
Published: November 2009

Purpose Our purpose is to present a case demonstrating a novel, rare retinal disorder, called "cone dystrophy with supernormal rod response".

Methods A 31‐year‐old female patient has been suffering from colour vision disturbances since her childhood. Her best corrected visual acuity is 0.2 in both eyes. Beyond routine ophthalmological methods we performed electrophysiological examinations, colour vision tests, dark adaptation, optical coherence tomography, fluorescein angiography and molecular genetic testing.

Results Examinations revealed colour vision disturbances, OCT showed macular thinning, FLAG demonstrated enlarged foveal avascular zone. Electroretinography showed extinguished cone function, preserved rod response and supernormal maximal b‐wave. Genetic tests confirmed mutation of the KCNV2 gene.

Conclusion "Cone dystrophy with supernormal rod response", known from recent literature, is a rare retinal disease, with the affection of the KCNV2 gene in the genetic background. Its stationery character is rare amongst cone dystrophies, congenital achromatopsia is the only one to have similar manifestation.
Role of dendritic cells in the ocular immune response
Authors: FORRESTER JV
Published: November 2009

Abstract not provided
Quantification of the photoreceptors of healthy retinas in rat by flow cytometry
Authors: TSOKA PA , PAPADAKI EA , TSILIMBARIS MK
Published: November 2009

Purpose The primary purpose of this study was to evaluate the potential to quantify photoreceptor population in the retina of healthy Spargue –Dawley rat in an accurate quantitative way by using flow cytometry. As far as we know, flow cytometry has not been used for photoreceptor quantification.

Methods Rats were killed and the eyes were enuclated to achieve retinal dissection. Tissue dissociation was accomplished with trypsin. Retinal cells were washed in PBS and permeabilized. The permeabilization was followed with the primary antibody incubation and then with the secondary antibody incubation.The analysis achieved in a flow cytometer. Flow cytometry was to measure physical and chemical characteristics in the photoreceptor population. Individual cells flow in suspension past one or more lasers scattering light and emitting fluorescence.

Results Quantification of photoreceptors was possible using flow cytometry. In this preliminary study, the photoreceptors had the 44,661 % in the hole mixed retinal population after anti‐rhodopsin staying.

Conclusion Flow cytometry can be used to quantify the different neuronal populations in control healthy eyes and this verification will be very useful in the futture in studies in apoptosis or proliferation of these cells.
Ophthalmic timolol in a hydrogel vehicle leads to minor interindividual variation in timolol concentration in aqueous humor
Authors: VAPAATALO H , VOLOTINEN M , MÄENPÄÄ J , KAUTIAINEN H , TOLONEN A , UUSITALO J , ROPO A , AINE E
Published: November 2009

Purpose Ophthalmic timolol has been used for decades in the treatment of glaucoma and ocular hypertension, traditionally in aqueous 0.5% eye drops. Recently a timolol 0.1% hydrogel has been developed to improve systemic safety. The aim of the present study was to compare aqueous humor timolol concentrations after administration of 0.1% hydrogel and aqueous 0.5% timolol in patients scheduled for a cataract operation.

Results The concentration in the aqueous humor was 210 ± 175 ng/ml (mean ± SD) two hours after administration of timolol 0.1% hydrogel and 538 ± 304 ng/ml after aqueous 0.5% timolol. In the aqueous 0.5% timolol group more patients had unnecessarily high concentrations of timolol in the aqueous humor. Beta 1‐receptors and Beta 2‐receptors were practically 100% occupied after administration of both products. The hydrogel proved to be an excellent formulation in giving smaller inter‐individual variation in penetration of timolol into the aqueous humor. Only a weak correlation was seen between corneal thickness and the aqueous humor concentration of timolol in the aqeuous 0.5% timolol group. A similar correlation was observed between age and concentration of timolol in the aqeuous 0.5% timolol group.

Conclusion In contrast to the conventional aqueous 0.5% timolol, 0.1% timolol hydrogel caused only slight inter‐individual variation in timolol concentration in the aqueous humor.
Much ado about nothing
Authors: VRENSEN G
Published: November 2009

May I introduce myself? I am a lens, one of the two you have. I look like a discus with my front less curved than my back. In good condition I am crystal clear and nearly colourless. When adult my diameter is 10mm, in the center I am 4mm thick and my weight is 250mg. I have a protected life, swimming in a small nicely warm pool, with water containing everything I need for living. I am hanging on thin strings in a trampoline. My back is supported by a huge soft waterbed. In front a round coloured iris is protecting me from too much sunlight. My only activity is regularly changing, in harmony with my fellow lens, my front and back curvature. As you see I am not very fascinating and I am surprised that my master and so many of his colleagues are spending so much time to me. Much ado about nothing!!! However, when looking around I see many young and old people wearing glasses, for reading and far vision. Big business; so many shops selling these glasses in expensive mounts. Moreover, when my master is consulting the homepages of the WHO it comes out that I am still the main cause of blindness world wide. In my master’s country lens blindness, also called cataract, is rare due to the fact that 130,000 of my fellow lenses are taken out per year and replaced by plastic lenses put in the thin bags surrounding us. Some 13,000‐26,000 of them are frustrating this surgery and their renewed cloudy backs are eliminated by laser bombardment. Imagine the enormous financial burden for this simple but very common treatment of cataract and after‐cataract. Much ado about nothing??? I am not as dull as I look at first glance. I am the only organ with no blood supply and no innervation. Food is coming in from the pool along small spaces between my fibers and my waste products are leaving through the fibers back to the pool. My center does not receive food at all. My most common cells: the fibres, are not shedded and I still contain all the fibers formed during my life span. For transparency my fibers have to loose their nuclei without dying; an unprecedented process. I am changing my curvatures without disturbing my internal structure. It is not surprising, however, that with all my metabolic and physiological handicaps, I become brown and opalescent in the end and am no longer able to help my ‘old’ master with reading. I am unique in many other aspects. So it is not surprising that many scientists got intrigued by my ingenuity to remain clear and active for nearly my whole life span. Much ado about nothing. No!!!
Flicker‐induced retinal vasodilataion ‐ what does a reduced response mean?
Authors: SCHMETTERER L
Published: November 2009

Purpose In the recent years much interest has been directed towards flicker‐induced vasodilatation. Various studies were done showing reduced flicker responses in diseases such as diabetic retinopathy or glaucoma. The basis for this reduced flicker responses is, however, largely unclear.

Methods Papers published on this topic in the last years were reviewed. Specific emphasis was directed towards publications that deal with potential mechanisms underlying flicker‐induced vasodilatation.

Results There is evidence from animal and human studies that flicker‐induced vasodilatation is at least partially dependent on nitric oxide. In addition, there is evidence to assume that flicker induces changes in the retinal glucose metabolism and the ratio of cytosolic NADH/NAD+ are involved.

Conclusion Flicker‐induced retinal vasodilatation appears to be partially endothelium‐dependent. It is, however, likely that other factors are also involved Further research is required to characterize the mechanisms underlying flicker‐induced vasodilatation in more detail. From a clinical point of view studies are needed to test the hypothesis that reduced retinal flicker responses are related to the prevalence, incidence and progression of ocular vascular disease.
Pharmacokinetics and ocular tissue penetration of VEGF trap after intravitreal injection in rabbits
Authors: STRUBLE C , KOEHLER‐STEC E , ZIMMER E , TU W
Published: November 2009

Purpose VEGF Trap is a potent antiangiogenic agent that binds and blocks the action of all VEGF‐A isoforms and placental growth factor and, is active in numerous animal models of age‐related ocular neovascularization and diabetic retinopathy, when administered either intravitreally or systemically. Moreover, systemic administration of VEGF Trap was active in reducing excess retinal thickness in a Phase I study in age‐related macular edema. To understand the pharmacokinetics following intravitreal administration, VEGF Trap (500 mcg) was administered to both eyes of pigmented rabbits.

Methods Plasma and eyes were harvested from three animals/time point at defined times to 4 weeks after administration. Concentrations of VEGF Trap, free and bound to VEGF, were determined in plasma, vitreous, choroid, and retina by ELISA.

Results Maximal vitreal concentrations of free VEGF Trap were approximately 500 mcg/mL at 0.25 to 6 hours after injection. The drug was cleared from the vitreous in a first order process with a half‐life of approximately 4.5 days. Vitreal VEGF:VEGF Trap complex reached a plarteau of 0.6 mcg/mL 10 days after administration. Drug was detected in both retina and choroid, and the elimination profile from these tissues approximated by that of the vitreous. Peak plasma total drug concentrations of 1.6 mcg/mL occurred at 10 days. At 4 weeks, the vitreal free VEGF Trap remained over 10‐fold in excess of bound VEGF Trap and the complex levels were on a plateau.

Conclusion Given the vitreal half‐life, free should remain in excess of bound for at least 3 additional half‐lives (13.5 days), suggesting that eye VEGF production would be completely blocked for more than 6 weeks after adminstration of of 500 mcg/eye of VEGF Trap.

Commercial interest
Study of candidate genes for ocular anterior segment dysgenesis (ASD)
Authors: D'HAENE B
Published: November 2009

Abstract not provided
Macular pigment and its correlation with colour vision and SWAP perimetry
Authors: DAVISON PA , LOUGHMAN J , SCANLON G , NOLAN J , BEATTY S
Published: November 2009

Purpose To investigate the effects of macular pigment optical density (MPOD) on colour vision and colour modulated visual fields using short‐wavelength automated perimetry (SWAP).

Methods Macular pigment (MP) spatial profile was measured using customised heterochromatic flicker photometry (cHFP) on 51 normal subjects. Colour vision was assessed using the Oculus anomaloscope [Moreland equation (AME)] and Farnsworth‐Munsell 100‐Hue (FM) with optimum confusion axes. A custom designed program on the Humphrey automated perimeter, was used to determine SWAP thresholds at the fovea, and at each degree of retinal eccentricity for the central five degrees. A 440nm Goldmann V stimulus presented on a 100cd/m2 bleaching background was used to isolate the short wave sensitive pathway.

Results While inter‐relationships were evident between AME, FM and SWAP, only one colour vision measure (on FM) correlated with MPOD (r=.302, p= 0.03). At similar degrees of eccentricity, SWAP was inversely and statistically significantly correlated with MPOD (e.g. 1‐degree retinal eccentricity: r = ‐0.198, p = 0.047; 3 degrees retinal eccentricity r = ‐0.290, p = 0.03).

Conclusion Colour vision, even using sensitive tests targeting blue‐yellow and blue‐green confusion is surprisingly independent of MPOD, while SWAP sensitivity is reduced with increased MPOD. We hypothesize that this is due to long‐term adaptation of the retinal blue‐yellow pathway to prevailing MPOD in normal subjects, this adaptation being upset by short‐term chromatic adaptation in SWAP.

Commercial interest
Retinal blood flow in patients with diabetes during normalized insulin and glucose plasma levels
Authors: WEIGERT G , POLSKA E , GARHOFER G , SCHMETTERER L
Published: November 2009

Purpose Ocular blood flow studies in patients with diabetes showed contradictory results. One of the reasons for these discrepancies is related to glycemic control, because glucose and insulin have been shown to induce ocular vasodilatation. Hence, we performed a study in diabetic patients measuring ocular blood flow during euglycemic euisoglycemic clamps.

Methods 16 patients with insulin dependent diabetes, no or mild non‐proliferative diabetic retinopathy and serum cholesterol levels < 250 mg/dl and 16 healthy sex‐ and age‐matched controls were included in the study. Retinal blood flow was measured in diabetic patients before the insulin morning dose and during euglycemic euinsulinemic clamps. For the assessment of retinal blood flow the Retinal Vessel Analyzer and bi‐directional laser Doppler velocimetry were used. All veins entering the optic nerve head were measured to gain information on total retinal blood flow.

Results Plasma glucose levels decreased from 176±21 mg/dl before morning insulin to 102±4 mg/dl during the euinsulinemic clamp. Retinal blood flow was reduced significantly from 51.4±5.5 µl/min before the clamp to 42.1±5.2µl/min during the euglycemic euinsulinemic clamps (p<0.01). As compared to the healthy control group retinal blood flow was increased before the clamps, but not during euglycemic euinsulinemic conditions.

Conclusion The present study indicates that retinal blood flow is increased in diabetic patients during high blood glucose levels. Retinal blood flow values are, however, comparable to healthy controls during euglycemic euisoglycemic clamps.
Outcome of transplanted mesenchymal stem cells in the alkali burned cornea
Authors: VERA L , LATOUCHE JB , GUEUDRY J , VANNIER JP , MURAINE M
Published: November 2009

Purpose Mesenchymal stem cells show promising results in cell therapy for many medical fields. We aimed to study their fate when transplanted in the inflammatory corneal environnement: survival, migration towards the injured tissues, differenciation.

Methods Plastic‐adherent, mononucleate cells derived from the bone marrow of New Zealand White rabbits, were transfected with Green Fluorescent Protein (GFP) and expanded in cultures. These MSCs were injected either directly in the stroma, or in the sub‐conjunctival space, six hours after the alkali burn of the center of the cornea. Immunohistochemistry and immnunofluorescence were performed one week to four weeks after the transplantation.

Results MSCs were detected by fluorescence microscopy at 7 days and 14 days after transplantation, whatever the site of injection. They were not present in our cut sections after two weeks. After the sub‐conjunctival injection, they were mostly localized at the limbus and the peripheral cornea. When transplanted directly in the stroma, they were more dispersed and remained at the site of injection. Fourteen days after transplantation, more than 90% of the MSCs expressed the a‐ smooth muscle actin marker, like residual keratocytes .MSCs never integrated the epithelial layers and did not express cytokeratins.

Conclusion These results suggest that MSCs transfected with GFP can migrate towards the damaged tissue when injected in the sub‐conjunctival space and survive during at least two weeks. They engraft to stromal cornea and differenciate rapidly into myofibroblasts. These MSCs are not able to differenciate into epithelial cells in our model. Their differenciation into myofibroblasts suggests that they might be involved in the stromal wound healing.
Is emmetropia the natural endpoint for human refractive development? An analysis of population‐based data from the refractive error study in children (RESC)
Authors: Morgan Ian G. , Rose Kathryn A. , Ellwein Leon B. ,   The Refractive Error Study in Children Survey Group
Published: November 2009

Acta Ophthalmol. 2010: 88: 877–884

Purpose:  To determine the natural end‐point for refractive development during childhood.

Methods:  Cycloplegic (1% cyclopentolate) autorefraction was performed on 38 811 children aged 5 and 15 in population‐based samples at eight sites in the Refractive Error Study in Children (RESC). Refractions (right eye) were categorized as myopic (≤−0.5 D), emmetropic (>−0.5 to ≤+0.5 D), mildly hyperopic (>+0.5 to ≤+2.0 D and hyperopic (>+2.0 D).

Results:  At five sites (Jhapa – rural Nepal, New Delhi – urban India, Mahabubnagar – rural India, Durban – semi‐urban South Africa and La Florida – urban Chile), there was <20% myopia by age 15. Mild hyperopia was the most prevalent category at all ages, except for Mahabubnagar where emmetropia became the marginally most prevalent category at ages 14 and 15. At the other sites (Gombak – semi‐urban Malaysia, Shunyi – semi‐rural China and Guangzhou – urban China), there was substantial (>35%) myopia by age 15. At these sites, mild hyperopia was the most prevalent category during early childhood, and myopia became the predominant category later. In Gombak district and Guangzhou, emmetropia was a minor category at all ages, with myopia increasing as mild hyperopia decreased. In Shunyi district, emmetropia was the most prevalent category over the ages 11–14.

Conclusion:  Emmetropia was not the predominant outcome for refractive development in children. Instead, populations were predominantly mildly hyperopic or substantial amounts of myopia appeared in them. This suggests that mild hyperopia is the natural state of refractive development in children and that emmetropia during childhood carries the risk of subsequent progression to myopia.
The wisdom behind third molar extractions
Authors: Kandasamy S , Rinchuse DJ , Rinchuse DJ
Published: November 2009

The literature pertaining to the extraction of third molars is extensive. There is a large individual variation and a multitude of practitioners’ beliefs and biases relating to the extraction of especially asymptomatic and pathology free third molars. With the current emphasis in dentistry being placed on clinicians to make evidence‐based decisions, the routine removal of third molars has been re‐assessed and questioned. The purpose of this paper was to evaluate past and present knowledge of third molar extractions and relate it to logical considerations relevant to science and the evidence‐based decision‐making process. This paper endeavours to encourage and stimulate clinicians to re‐evaluate their views on third molar extractions based on suggested guidelines and current evidence.
Predictable management of cracked teeth with reversible pulpitis
Authors: Abbott P , Leow N
Published: November 2009

Background:  The aims of this study were to assess symptoms and signs caused by cracks in teeth and to assess a conservative management protocol.

Methods:  The symptoms and signs of 100 consecutive teeth that had reversible pulpitis associated with cracks were compared to findings from other reports. Teeth were managed with a conservative protocol which involved removal of cracks, caries and restorations, followed by placement of a sedative lining and interim restoration unless there were pulp exposures or insufficient tooth structure remaining. Teeth were monitored for pulp healing after three months and for up to five years.

Results:  Eighty teeth did not require endodontic treatment. One tooth had an uncertain pulp status at review appointments. Fifteen teeth required endodontic treatment at the initial appointment because of carious pulp exposures (4 teeth), cracks extending into the pulp (2), and posts required (9). Four other teeth required endodontic treatment later following conservative pulp treatment due to continued pulpitis under the temporary restoration (1), pulpitis after core restoration (2), and pulp necrosis diagnosed at the review (1).

Conclusions:  Provided there is an accurate diagnosis of the pulp status and its cause, teeth with reversible pulpitis due to cracks can be treated conservatively without endodontic treatment in about 80 per cent of cases.
Shear bond strength of luting agents to fixed prosthodontic restorative core materials
Authors: Capa N , Özkurt Z , Canpolat C , Kazazoglu E
Published: November 2009

Background:  Bonding properties of luting cements are important for retention of restorative core materials. The aim of this study was to compare the bonding performance of a resin‐modified glass ionomer cement and a self‐adhesive resin cement to various fixed prosthodontic core materials.

Methods:  Cylindrical specimens with a thickness of 2 mm and a diameter of 5 mm were fabricated from Au‐Pd‐Ag, Co‐Cr, Ni‐Cr‐Mo, Ni‐Cr‐Fe alloys, titanium, zirconia and Empress II (n = 20). Each group was divided into two subgroups to be luted with two different luting agents. Composite resin blocks were cemented onto specimens with RelyXUnicem and FujiCem. A shear bond strength machine with 50 kg load cell and 0.50 mm/min crosshead speed was used. Kruskal Wallis test, Dunn’s Multiple Range test and Mann‐Whitney‐U test were used for statistical analysis. The results were evaluated in a confidence interval of p < 0.05.

Results:  The highest bond strength was obtained between Ni‐Cr‐Fe‐RelyXUnicem (8.22 ± 2.15 MPa) and the lowest was between Empress II‐FujiCem (1.48 ± 0.9 MPa). In FujiCem groups, Co‐Cr and Ni‐Cr‐Fe showed significantly higher bond strength than Au‐Pd‐Ag and Empress II. In RelyX Unicem groups, Ni‐Cr‐Fe showed higher bond strength than Empress II.

Conclusions:  The types of luting agents and restorative core materials may have a significant influence on bond strength.
Gas Void Fraction Measurement in Two-Phase Gas/Liquid Slug Flow Using Acoustic Emission Technology
Authors: Al-lababidi S. , Addali A. , Yeung H. , Mba D. , Khan F.
Published: November 2009

The gas-liquid two-phase slug flow regime phenomenon is commonly encountered in the chemical engineering industry, particularly in oil and gas production transportation pipelines. Slug flow regime normally occurs for a range of pipe inclinations, and gas and liquid flowrates. A pipeline operating in the slug flow regime creates high fluctuations in gas and liquid flowrates at the outlet. Therefore, the monitoring of slugs and the measurement of their characteristics, such as the gas void fraction, are necessary to minimize the disruption of downstream process facilities. In this paper, a correlation between gas void fraction, absolute acoustic emission energy, and slug velocities in a two-phase air/water flow regime was developed using an acoustic emission technique. It is demonstrated that the gas void fraction can be determined by measurement of acoustic emission.
Multimode Dynamics and Out-of-Plane Drift in Suspended Cable Using the Kinematically Condensed Model
Authors: Wang Lianhua , Zhao Yueyu , Rega Giuseppe
Published: November 2009

The large amplitude vibration and modal interactions of shallow suspended cable with three-to-three-to-one internal resonances are investigated. The quasistatic assumption and direct approach are used to obtain the condensed suspended cable model and the corresponding modulation equations for the case of primary resonance of the third symmetric in-plane or out-of-plane mode. The equilibrium, periodic, and chaotic solutions of the modulation equations are studied. Moreover, the nonplanar motion and symmetric character of out-of-plane vibration of the shallow suspended cables are investigated by means of numerical simulations. Finally, the role played by the quasistatic assumption, internal resonance, and static configuration in disrupting the symmetry of the out-of-plane vibration is discussed.
EPID dosimetry: Effect of different layers of materials on absorbed dose response
Authors: Gustafsson Helen , Vial Philip , Kuncic Zdenka , Baldock Clive , Greer Peter B.
Published: November 2009

Purpose:

Commercial EPIDs are normally used in indirect detection mode (iEPID) where incident x‐ray photons are converted to optical photons in a phosphor scintillator, which are then detected by a photodiode array. The EPIDs are constructed from a number of nonwater equivalent materials which affect the dose response of the detector. The so‐called direct detection EPIDs (dEPIDs), operating without the phosphor layer, have been reported to display dose response close to in‐water data. In this study, the effect that different layers of materials in the EPID have on the dose response was experimentally investigated and evaluated with respect to changes in field size response and beam profiles.

Methods:

An iEPID was disassembled and the different layers of materials were removed or replaced with other materials. Data were also obtained on and off the support arm and with a sheet of opaque paper blocking the optical photons from the gadolinium oxysulfide phosphor layer. Field size response was measured for field sizes ranging from , and profiles for the beams were extracted from the data.

Results:

The iEPID configuration was found to be very sensitive to backscatter. The increases in output with solid water backscatter compared to the no backscatter case were 14.7% and 6.6% at the largest field size investigated for the 6 and beams, respectively. The phosphor layer had a large influence on field size response as well as beam profiles for photons, while no major effects were observed for the beam. For large differences in dose response were found when the standard Cu buildup was changed for equivalent Cu or solid water buildup, indicating that head scatter largely influences dose response for this energy. When the optical photons originating in the layer were blocked from reaching the photodiodes, both field size output data and beam profiles corresponded well with data obtained in the dEPID configuration as well as reference ion chamber data for both energies.

Conclusions:

As expected, changing the layers of material in the EPID had a dramatic effect on dose response, which was often quite complex. For, the complex dose response is mainly caused by the optical photons from the layer, while insufficient filtering of scattered radiation largely affects the dose response for the beam. The iEPID was also found to be very sensitive to backscatter for both energies. Blocking the optical photons created in the layer essentially changed the iEPID configuration into the dEPID configuration, thus demonstrating great potential for a system that can be optimized for both imaging and dosimetry.
The myth of the 50‐50 breast
Authors: Yaffe M. J. , Boone J. M. , Packard N. , Alonzo‐Proulx O. , Huang S.‐Y. , Peressotti C. L. , Al‐Mayah A. , Brock K.
Published: November 2009

Purpose:

For dosimetry and for work in optimization of x‐ray imaging of the breast, it is commonly assumed that the breast is composed of 50% fibroglandular tissue and 50% fat. The purpose of this study was to assess whether this assumption was realistic.

Methods:

First, data obtained from an experimental breast CT scanner were used to validate an algorithm that measures breast density from digitized film mammograms. Density results obtained from a total of 2831 women, including 191 women receiving CT and from mammograms of 2640 women from three other groups, were then used to estimate breast compositions.

Results:

Mean compositions, expressed as percent fibroglandular tissue (including the skin), varied from 13.7% to 25.6% among the groups with an overall mean of 19.3%. The mean compressed breast thickness for the mammograms was 5.9 cm. 80% of the women in our study had volumetric breast density less than 27% and 95% were below 45%.

Conclusions:

Based on the results obtained from the four groups of women in our study, the “50‐50” breast is not a representative model of the breast composition.
A Monte Carlo estimation of effective dose in chest tomosynthesis
Authors: Sabol John M.
Published: November 2009

Purpose:

The recent introduction of digital tomosynthesis imaging into routine clinical use has enabled the acquisition of volumetric patient data within a standard radiographic examination. Tomosynthesis requires the acquisition of multiple projection views, requiring additional dose compared to a standard projection examination. Knowledge of the effective dose is needed to make an appropriate decision between standard projection, tomosynthesis, and CT for thoracic x‐ray examinations. In this article, the effective dose to the patient of chest tomosynthesis is calculated and compared to a standard radiographic examination and to values published for thoracic CT.

Methods:

Radiographic technique data for posterior‐anterior (PA) and left lateral (LAT) radiographic chest examinations of medium‐sized adults was obtained from clinical sites. From these data, the average incident air kerma for the standard views was determined. A commercially available tomosynthesis system was used to define the acquisition technique and geometry for each projection view. Using Monte Carlo techniques, the effective dose of the PA, LAT, and each tomosynthesis projection view was calculated. The effective dose for all projections of the tomosynthesis sweep was summed and compared to the calculated PA and LAT values and to the published values for thoracic CT.

Results:

The average incident air kerma for the PA and left lateral clinical radiographic examinations were found to be 0.10 and, respectively. The effective dose for the PA view of a patient of the size of an average adult male was determined to be (ICRP 60) [ (ICRP 103)]. For the left lateral view of the same sized patient, the effective dose was determined to be (ICRP 60) [ (ICRP 103)]. The cumulative mA s for a tomosynthesis examination is recommended to be ten times the mA s of the PA image. With this technique, the effective dose for an average tomosynthesis examination was calculated to be (ICRP60) [ (ICRP103)]. This is less than 75% of that predicted by scaling of the PA mA s ratio. This lower dose was due to changes in the focal‐spot‐to‐skin distance, effective changes in collimation with projection angle, rounding down of the mA s step, and variations in organ exposure to the primary x‐ray beam for each view. Large errors in dose estimation can occur if these factors are not accurately modeled.

Conclusions:

The effective dose of a chest examination with this chest tomosynthesis system is about twice that of a two‐view chest examination and less than 2% of the published average values for thoracic CT. It is shown that complete consideration of the tomosynthesis acquisition technique and geometry is required for accurate determination of the effective dose to the patient. Tomosynthesis provides three‐dimensional imaging at a dose level comparable to a two‐view chest x‐ray examination and may provide a low dose alternative to thoracic CT for obtaining depth information in chest imaging.
Energy dependence of EBT‐1 radiochromic film response for photon and electron beams readout by a flatbed scanner
Authors: Richter Christian , Pawelke Jörg , Karsch Leonhard , Woithe Julia
Published: November 2009

Purpose:

The aim of this article is to investigate the energy dependence of the radiochromic film type, Gafchromic™ EBT‐1, when scanned with a flatbed scanner for film readout.

Methods:

Dose response curves were determined for 12 different beam qualities ranging from a x‐ray beam to a x‐ray beam and include also two high energy electron beam qualities (6 and ). The dose responses measured as net optical density (netOD) for the different beam qualities were normalized to the response of a reference beam quality .

Results:

A strong systematic energy dependence of the film response was found. The lower the effective beam energy, the less sensitive the EBT‐1 films get. The maximum decrease in dose for the same film response between the and beam qualities was 44%. Additionally, a difference in energy dependence for different doses was discovered, meaning that higher doses show a smaller dependency on energy than lower doses. The maximum decrease in the normalized netOD was found to be 25% for a dose of relative to the normalized netOD for . Moreover, a scaling procedure is introduced, allowing the correction of the energy dependence for the investigated beam qualities and also for comparable x‐ray beam qualities within the energy range studied.

Conclusions:

A strong energy dependence for EBT‐1 radiochromic films was found. The films were readout with a flatbed scanner. If the effective beam energy is known, the energy dependence can be corrected with the introduced scaling procedure. Further investigation of the influence of the spectral band of the readout device on energy dependence is needed to understand the reason for the different energy dependences found in this and previous works.
Trial of a proposed protocol for constancy control of digital mammography systems
Authors: Pedersen Kristin , Landmark Ingrid Dypvik
Published: November 2009

Purpose:

Evaluate the utility of tests in a proposed protocol for constancy control of digital mammography systems.

Methods:

The protocol contained tests for image acquisition, mechanical function and safety, monitors and printers, and viewing conditions. Nine sites with digital systems from four equipment manufacturers were recruited. Dedicated PMMA test objects and Excel spreadsheets were developed. Quantitative measurements were done on processed images for systems where these images were the ones most readily available. For daily assessment of the automatic exposure control system, a homogeneous PMMA phantom was exposed under clinical conditions. The mAs and signal to noise ratio (SNR) were recorded, the deviation from a target value calculated, and the resulting image inspected for artifacts. For thickness tracking, the signal difference to noise ratio obtained for three thicknesses was calculated. Detector uniformity was assessed through comparison of SNR values for regions of interest in the center and corners of an image of a homogeneous test object. Mechanical function and safety control included a compression test, a checklist for mechanical aspects, and control of field alignment. Monitor performance was evaluated by visual inspection of the AAPM TG 18 QC test image [E. Samei et al., “Assessment of display performance for medical imaging systems,” Task Group 18 (Madison, WI, April 2005)].

Results:

For quantitative parameters, target values and tolerance limits were established. Test results exceeding the limits were registered. Most systems exhibited stable mAs values, indicating that the tolerance limit of was readily achievable. The SNR also showed little variation, indicating that the tolerance limit of was too wide. At one site, a defective grid caused artifacts that were visible in the test images. The monitor controls proved more difficult to implement due to both difficulties importing and displaying the test image, and the radiographic technologists not getting necessary access to the reading stations.

Conclusions:

The proposed tests could easily be performed by trained radiographic technologists and within a time frame comparable to similar programs for analog systems. Tests with quantitative measures were more readily performed than procedures that required a subjective evaluation. Several of the proposed tests revealed equipment performance that required intervention, and which would otherwise have gone unnoticed. They therefore defend a place in a vendor‐independent constancy control protocol.