A conceptual model for changes in finger photoplethysmograph signals caused by hand posture and isothermic regulation.

Objective. To observe changes in baseline position and pulsatile light absorbance (photoplethysmograph, PPG) in the finger-tip, by raising the hand above the horizontal plane in recumbent subjects. We applied current knowledge of the circulation to the finger-tip, particularly arteriovenous anastomoses (AVAs), and the physiology of the venous circulation.Approach.We studied healthy young volunteers in a quiet thermoneutral environment. A finger plethysmograph on the non-dominant hand recorded transmission of red and infra-red light, with observations expressed as absorbance to allow comparisons within and between subjects. Breathing movements were recorded unobtrusively to assess any effect on absorbance and the pulse amplitude of the signals. All body movements were passive: the study arm was elevated in a trough to about 40° above the horizontal plane. The following conditions were studied, each for 15 min, using the last 10 min for analysis: recumbent, study arm elevated, study arm horizontal, and both legs elevated by 40°.Main results. We found a substantial time-related effect, and considerable variation between subjects. Arm elevation reduced red light absorbance and increased the range of amplitudes of the PPG waveform: only in subjects with large absorbances, did waveform amplitude increase. Spontaneous, thermoregulatory decreases in absorbance were large and associated with decreases in waveform amplitude.Significance. Finger-tip vessels distend with blood and light absorbance increases when AVAs open. The vessels pulsate more strongly when the hand is raised: venous collapse allows the vessels to become more compliant. The postcapillary circulation is likely to be an important source of pulsation.

Health, perceived quality of life and health services use among homeless illicit drug users.

INTRODUCTION: Drug misuse has been identified as a significant problem in homeless populations. This study examines aspects of physical and mental health, perceived quality of life and health service use among homeless illicit drug users and compares these to non-drug users. METHODS: Participants were recruited through health clinics across Dublin. A questionnaire assessed participants' drug use, health and well-being, health behaviours and use of health services. Descriptive statistics are presented for the entire cohort and drug users separately. Logistic regression analysis was used to examine the relationship between drug use and (i) multimorbidity, (ii) anxiety and/or depression, (iii) perceived quality of life and (iv) use of health services. RESULTS: Of 105 participants recruited, 35 (33%) were current drug users. Current and previous drug users were significantly more likely to have multimorbidity than those who had never taken drugs (OR 4.86, 95% CI 1.00-23.66). There was no significant difference between drug users and non-drug users in the prevalence of anxiety and/or depression. Drug users were five times more likely than non-drug users to have a low perceived quality of life (OR 5.2, 95% CI 1.7-16.0). Health service utilization was high, although some services were used less by drug users (e.g., dentist and psychiatric outpatient services) while others were used more often (e.g., phoneline services and day care centres). CONCLUSION: This study highlights the high levels of drug use in this population and the negative impact of drug use on health and perceived quality of life of a homeless population in Dublin.

Should patients with infrainguinal arterial bypasses using autologous vein conduit undergo follow-up surveillance with duplex ultrasound?

This best evidence topic was investigated according to a structured format. The question asked was: should duplex ultrasound (DUS) scanning be a routine component of surveillance following infrainguinal arterial bypass using vein conduit? We performed a systematic literature search and identified 4 studies (3 randomised controlled trials and 1 meta-analysis) that provided the best evidence. The highest quality study was a multi-centre randomised controlled trial (n = 594). At 18 months following surgery, it found no difference in patency rates, amputations, vascular mortality or mortality. However it achieved just over half of anticipated recruitment and thus was underpowered. The remaining two randomised controlled trials had smaller sample sizes and methodological weaknesses and found conflicting results. Lundell et al. (n = 106) found improved primary assisted and secondary patency rates and fewer graft occlusions with a routine DUS policy. Ihlberg et al. (n = 152) found no difference in primary assisted patency or amputations although secondary patency was improved. A meta-analysis of mostly observational data (n = 6649) found fewer occlusions with routine DUS surveillance and no effect on amputations or mortality. Results are conflicting. The strongest evidence comes from the single high quality multi-centre trial. It appears as though routine DUS surveillance does not yield benefits in patient important outcomes. Further studies are needed.

Assessing the quality of online information for patients with carotid disease.

INTRODUCTION: Controversy exists relating to carotid endarterectomy (CEA) versus carotid artery stenting (CAS). We aimed to assess the quality of online patient information relating to both. METHODS: The Google search engine was searched for "carotid endarterectomy" and "carotid stenting". The first 50 webpages returned were assessed. The Gunning Fog Index (GFI) and Flesch Reading Ease Score (FRES) were calculated to assess readability. The LIDA tool (Minervation Ltd., Oxford, U.K.) was used to assess accessibility, usability and reliability. RESULTS: 20% (n = 10) of the webpages returned for CEA were from peer reviewed sources with 34% (n = 17) posted by hospitals or health services. Comparatively, for CAS, 40% (n = 20) were peer reviewed with 16% (n = 8) posted by hospitals or health services. GFI and FRES scores indicated webpages for both CEA and CAS had poor general readability. Webpages for CEA were easier to read than those for CAS (mean FRES difference of 6.7 (95% CI 0.51 to 12.93, p = 0.03). Median LIDA scores demonstrated acceptable reliability, accessibility and usability of information for both CEA and CAS webpages. The more readable webpages were not associated with higher LIDA scores for either CEA or CAS webpages. CONCLUSION: Webpages providing information on carotid disease management must be made more readable. Online information currently available to patients regarding CAS is more difficult to read and comprehend than CEA.

Antibiotic prescribing trends in a paediatric sub-population in Ireland.

PURPOSE: Little is known about antibiotic prescribing in Irish children. This study aims to examine antibiotic prescribing patterns in Irish children and associated costs and to compare this with European findings. METHODS: A retrospective analysis of the Irish Health Services Executive (HSE) pharmacy claims database 2004-2009 for the General Medical Services (GMS) scheme for dispensed medications. This represents 28% of Irish children but over-represents lower socio-economic groups. Overall prescribing rates were reported over time (2004-2009), age (0-4, 5-11, 12-15 years) and gender. Statistical comparison is made using negative binomial regression. Overall prescribing rates for the most commonly prescribed drugs were calculated. Associated cost of prescribing also was calculated. European prescribing data were retrieved from the literature. RESULTS: Rates remained stable from 2004 (631/1000 GMS population; 95%CI 628-634) to 2009 (621/1000; 95%CI 618-624). An interaction effect emerged between gender and age. Rates were generally higher for girls, except for the boys aged 0-4 years. The preferred choice of agents changed across years, with co-amoxiclav becoming the most prescribed drug in 2009 (308/1000; 95%CI 306-310). The total cost of antibiotics increased from €4.4 million in 2004 to €6.0 million in 2009. Higher overall rates of antibiotic prescribing emerged compared with available European data. Differences were observed between prescribing of some first-line and second-line drugs. CONCLUSIONS: Age and gender trends are consistent with international literature. However, Ireland has higher overall prescribing rates relative to some European countries. This suggests that a quality improvement in prescribing intervention is warranted.

Proximal component modularity in THA--at what cost? An implant retrieval study.

BACKGROUND: While modular femoral heads have been used in THA for decades, a recent innovation is a second neck-stem taper junction. Clinical advantages include intraoperative adjustment of leg length, femoral anteversion, and easier revision, all providing flexibility to the surgeon; however, there have been reports of catastrophic fracture, cold welding, and corrosion and fretting of the modular junction. QUESTIONS/PURPOSES: We asked whether (1) the neck-stem junction showed the same degradation mechanisms, if any, as the head-neck junction, (2) the junction contributed to THA revision, (3) the alloy affected the degree of degradation, and (4) the trunion machine finish affected the degradation mechanisms. METHODS: We compared 57 retrievals from seven total hip modular designs, three cobalt-chromium-molybdenum and four titanium based: Bionik(®) (four), GMRS(®) (four), Margron(®) (22), Apex(®) (five), M-series(®) (five), ZMR(®) (two), and S-ROM(®) (15). Macroscopic inspection, microscopy, and micro-CT were conducted to determine the effects of materials and design. RESULTS: The cobalt-chromium-molybdenum components showed crevice corrosion and fretting of the neck-stem taper, whereas the titanium components had less corrosion; however, there were several cases of cold welding where disassembly could not be achieved in theater. CONCLUSIONS: Even with modern taper designs and corrosion-resistant materials, corrosion, fretting, and particulate debris were observed to a greater extent in the second neck-stem junction. Titanium-based modular arthroplasty may lessen the degree of degradation, but cold welding of the components may occur. CLINICAL RELEVANCE: Degradation of the second junction contributed to 8 cases of metallosis and two cases of aseptic lymphocyte-laminated vascular-associated lesions contributing to revision.

A case report of synchronous osteoblastoma and fibromatosis.

Osteoblastoma is a rare bone tumour that accounts for 1% of all primary bone tumours and 3% of all benign bone tumours. Osteoblastoma occurring in long bones has a predilection for the meta-diaphysis. It bears a close histological resemblance to osteoid osteoma, but it is not growth limited - usually 2 cm or greater at diagnosis. The term "fibromatosis" covers a broad spectrum of benign fibrous tissue proliferations. It is characterized by infiltrative growth and a tendency for recurrence; however, unlike sarcoma, it never metastasizes. To our knowledge, this is the first case report in the English literature of a patient with synchronous presentation of an osteoblastoma and fibromatosis.

Essentials of shoulder MR arthrography: a practical guide for the general radiologist.

Lesions of the glenoid labrum and ligamentous structures commonly occur secondary to shoulder trauma and are a frequent cause of shoulder joint instability. Numerous eponyms, acronyms and subclassifications are used to describe the often confusing array of bony and labro-ligamentous abnormalities of the shoulder. This aim of this review is to illustrate the relevant features of these lesions and to provide a systematic and practical approach to imaging of the shoulder using MR arthrography.

Local mu and delta opioid receptors regulate amphetamine-induced behavior and neuropeptide mRNA in the striatum.

The purpose of this study was to investigate the role that mu and delta opioid receptor blockade has upon stimulant-induced behavior and neuropeptide gene expression in the striatum. Acute administration of amphetamine (2.5 mg/kg i.p.) caused an increase in behavioral activity and preprodynorphin, substance P, and preproenkephalin mRNA expression. Intrastriatal infusion of the mu opioid antagonist, H-D-Phe-Cys-Tyr-D-Trp-Arg-Thr-Pen-Thr-NH(2) (CTAP), or the delta opioid antagonist, H-Tyr-Tic[CH(2)NH]-Phe-Phe-OH (TIPPpsi), significantly decreased amphetamine-induced vertical activity. However, only CTAP reduced amphetamine-induced distance traveled. Quantitative in situ hybridization histochemistry revealed that CTAP blocked amphetamine-induced preprodynorphin and substance P mRNA. However, preproenkephalin mRNA levels in the dorsal striatum were increased to the same extent by CTAP, amphetamine, or a combination of the two drugs. In contrast, TIPPpsi significantly decreased amphetamine-induced mRNA expression of all three neuropeptides. These data indicate that both mu and delta receptor subtypes differentially regulate amphetamine-induced behavior and neuropeptide gene expression in the rat striatum.

The imaging spectrum of Baker's (Popliteal) cysts.

Baker's (Popliteal) cysts are frequently encountered on cross-sectional imaging of the knee. These consist of enlarged gastrocnemius semimembranosus bursa which typically communicate with the knee. They may be imaged with a variety of techniques including arthopgraphy, CT, ultrasound and MRI, with the latter two being more commonly used. Examples of bursa imaged with all of the above techniques are demonstrated in the essay, as well as variance of normal appearance and pathological entities including ruptured bursa, abnormally positioned bursa, osteochondromatosis, septic complications of the bursa and pigmented villonodular synovitis.

Von Hippel-Lindau disease: a radiological essay.

Von Hippel-Lindau disease is a progressive autosomal dominant disorder with multi-organ involvement. A variety of benign and malignant disease processes lie within the spectrum of disease processes associated with this condition. Early detection and treatment of complications is paramount in the management of these patients. The purpose of this pictorial review is to depict the various radiological manifestations that are commonly seen in this disease.

Fractured Whiteside Ortholoc II knee components.

A comprehensive failure analysis was performed on 6 femoral components and 1 tibial component that fractured in service. All were Whiteside Ortholoc II total knee arthroplasty components, manufactured from cast cobalt-chromium-molybdenum alloy and porous coated. Fracture surface analysis revealed fatigue-induced failure in all cases. Most fractures occurred at regions of high stress concentration, such as sharp corners, sintered beads, and thin sections. Metallurgical examination showed significant variation in grain size, interdendritic carbides, and hardness between samples. In some cases, continuous carbide networks and voids were prominent at the bead-substrate interface. Patient weight and surgical placement were identified as contributory factors in component failure. Limitations of cast cobalt-chromium-molybdenum alloy in weight-bearing applications must be emphasized, particularly when important determinants, such as design, metallurgy, and specific clinical factors, are less than optimal.

The "dependent viscera" sign in CT diagnosis of blunt traumatic diaphragmatic rupture.

OBJECTIVE: The objective of our study was to describe the "dependent viscera" sign and determine its usefulness at CT in the diagnosis of diaphragmatic rupture after blunt abdominal trauma. MATERIALS AND METHODS: The study sample consisted of 28 consecutive patients (19 men, nine women) between 17 and 74 years old (mean age, 31 years) who had undergone abdominal CT and subsequent emergency laparotomy after a blunt trauma. Ten patients had a diaphragmatic rupture (six, right-sided; four, left-sided) at laparotomy. An experienced radiologist unaware of the surgical findings retrospectively reviewed the CT scans, and then a second radiologist reviewed the scans to provide interobserver agreement. Note was made of discontinuity of the diaphragm, intrathoracic herniation of abdominal contents, and waistlike constriction of bowel (the collar sign). Also noted was whether the upper one third of the liver abutted the posterior right ribs or whether the bowel or stomach lay in contact with the posterior left ribs. Either of these findings was termed the "dependent viscera" sign. The radiologists' detection rate of diaphragmatic rupture on the CT scans via observance of the dependent viscera sign was determined. Interobserver agreement was assessed using Cohen's kappa statistic. RESULTS: The dependent viscera sign was observed on the CT scans of 100% of the patients with a left-sided diaphragmatic rupture and of 83% of the patients with right-sided diaphragmatic rupture. Both observers missed one case of right-sided diaphragmatic rupture. The radiologists' overall rate of detecting diaphragmatic rupture was 90% using the dependent viscera sign. We found excellent interobserver agreement (kappa = 1) for detection of the dependent viscera sign and for the diagnosis of diaphragmatic tear on CT scans. CONCLUSION: The dependent viscera sign increases the detection at CT of acute diaphragmatic rupture after blunt trauma.

MR imaging of bone oedema: mechanisms and interpretation.

Widespread use of MRI now allows the routine identification of previously unevaluated traumatic bone marrow oedema and haemorrhage. Similar marrow oedema is identified in patients with tumours, hyperaemia and medullary congestion. Patterns and extent of traumatic bone marrow oedema and haemorrhage are dictated by mechanism. Diffusion techniques may allow precise evaluation of severity of injury. Illustrative examples and discussion are presented. Eustace, S. (2001). Clinical Radiology56, 4-12.

Is it real or is it an artifact.

Sonographic artifacts are inherent to the modality and occur to some extent in every image. This is despite optimal technique and scanning parameters. Artifacts occur in both gray-scale and color Doppler imaging, and though many are readily recognizable as such, occasionally, an artifact may obscure the diagnosis or even create false pathology. This article illustrates the common and some of the more unusual sonographic artifacts that may be encountered, reviews the factors leading to their formation, and discusses strategies to recognize and minimize these misleading echoes.

MR imaging of bone tumors of the cervical spine.

MR Imaging has altered radically the detection, characterization, and the staging of bone tumors. This article reviews MR imaging techniques and appearances of benign and malignant bone tumors that are encountered in the cervical spine.

Interleukin-6 gene-deficient mice show impaired defense against pneumococcal pneumonia.

Induction of pneumonia in C57Bl/6 mice by intranasal inoculation with 10(6) cfu of Streptococcus pneumoniae resulted in sustained expression of interleukin (IL)-6 mRNA in lungs and increases in lung and plasma IL-6 concentrations. In IL-6-deficient (IL-6-/-) mice, pneumonia was associated with higher lung levels of the proinflammatory cytokines tumor necrosis factor-alpha, IL-1beta, and interferon-gamma and of the antiinflammatory cytokine IL-10 than in wild type (IL-6+/+) mice (all P < .05). Also, the plasma concentrations of soluble tumor necrosis factor receptors were higher in IL-6-/- mice (P < .05), while the acute-phase protein response was strongly attenuated (P < .01). Lungs harvested from IL-6-/- mice 40 h after inoculation contained more S. pneumoniae colonies (P < .05). IL-6-/- mice died significantly earlier from pneumococcal pneumonia than did IL-6+/+ mice (P < .05). During pneumococcal pneumonia, IL-6 down-regulates the activation of the cytokine network in the lung and contributes to host defense.