A qualitative evaluation of internet information on hip and knee osteoarthritis.

BACKGROUND: Hip and knee arthritis are two of the most common conditions that result in referral to orthopaedic outpatient clinics. Many patients now use the internet to research their condition and to inform their decision about treatment options. This has implications for the process of informed consent. AIM: To assess the quality of patient information on the internet regarding hip and knee arthritis. METHODS: 'Hip arthritis' and 'Knee arthritis' were entered as search terms into a popular search engine. To adjust for temporal variation, the process was repeated one month and one year later. Of the 200 results analysed, 83 websites met the inclusion criteria. The quality of patient information presented on these websites was assessed using a validated scoring instrument by two independent observers. RESULTS: Most websites assessed were of poor quality; nearly half of all websites did not mention any risks or complications associated with surgical intervention for these conditions. CONCLUSIONS: As part of their professional obligation to provide a robust process of informed consent, clinicians should be aware of the variable quality of patient information available on the internet. As such, they should be prepared to advise their patients about quality websites where reliable information can be sought.

Numerical Simulations of Realistic Lead Trajectories and an Experimental Verification Support the Efficacy of Parallel Radiofrequency Transmission to Reduce Heating of Deep Brain Stimulation Implants during MRI.

Patients with deep brain stimulation (DBS) implants may be subject to heating during MRI due to interaction with excitatory radiofrequency (RF) fields. Parallel RF transmit (pTx) has been proposed to minimize such RF-induced heating in preliminary proof-of-concept studies. The present work evaluates the efficacy of pTx technique on realistic lead trajectories obtained from nine DBS patients. Electromagnetic simulations were performed using 4- and 8-element pTx coils compared with a standard birdcage coil excitation using patient models and lead trajectories obtained by segmentation of computed tomography data. Numerical optimization was performed to minimize local specific absorption rate (SAR) surrounding the implant tip while maintaining spatial homogeneity of the transmitted RF magnetic field (B1+), by varying the input amplitude and phase for each coil element. Local SAR was significantly reduced at the lead tip with both 4-element and 8-element pTx (median decrease of 94% and 97%, respectively), whereas the median coefficient of spatial variation of B1+ inhomogeneity was moderately increased (30% for 4-element pTx and 20% for 8-element pTx) compared to that of the birdcage coil (17%). Furthermore, the efficacy of optimized 4-element pTx was verified experimentally by imaging a head phantom that included a wire implanted to approximate the worst-case lead trajectory for localized heating, based on the simulations. Negligible temperature elevation was observed at the lead tip, with reasonable image uniformity in the surrounding region. From this experiment and the simulations based on nine DBS patient models, optimized pTx provides a robust approach to minimizing local SAR with respect to lead trajectory.

Reaction time-monitored patient-maintained propofol sedation: a pilot study in oral surgery patients.

Previous volunteer studies of an effect-site controlled patient-maintained sedation system using propofol have demonstrated a risk of oversedation. We have incorporated a reaction time monitor into the handset to add an individualised patient-feedback mechanism. This pilot study assessed if the reaction time-feedback modification would prove safe and effective in 20 healthy patients receiving sedation while undergoing oral surgery. All patients successfully sedated themselves without reaching any unsafe endpoints. All 20 maintained verbal contact throughout. The mean (SD) lowest peripheral blood oxygen saturation was 98.0 (2.1)% breathing room air. No patient required supplementary oxygen. The mean (SD) maximum effect-site propofol concentration reached was 1.6 (0.5) µg.ml(-1). The present system was found to be safe and effective, allowing oral surgery treatment under conscious sedation, but preventing oversedation.

The effect of propofol on patient reaction time and its relationship with loss of verbal contact before induction of anaesthesia.

Increasing the calculated plasma concentration of propofol has been shown to increase choice reaction time and visual and auditory response times. We studied the relationship of reaction to a vibrating handset as the effect-site target-controlled propofol concentration was incrementally increased in 20 patients during sedation, before induction of general anaesthesia. The reaction time increased, initially slowly and then more rapidly, as the calculated effect-site concentration of propofol increased, until the reaction to the vibrating handset was lost at a mean (SD) propofol effect-site concentration of 2.0 (0.6) µg.ml(-1) . The loss of response to verbal contact occurred at a propofol effect-site concentration of 2.4 (0.5) µg.ml(-1) . Reaction time may be of use clinically to warn of impending loss of verbal contact.

Patient-maintained propofol sedation using reaction time monitoring: a volunteer safety study.

Previous volunteer studies of an effect-site controlled, patient-maintained sedation system using propofol have demonstrated a risk of over-sedation. We have incorporated a reaction-time monitor into the handset of the patient-maintained sedation system to add an individualised patient-feedback mechanism. This study assessed if such reaction-time feedback modification would reduce the risk of over-sedation in 20 healthy volunteers deliberately attempting to over-administer themselves propofol. All the volunteers successfully sedated themselves without reaching any unsafe endpoints. All volunteers maintained verbal contact throughout, in accordance with the definition of conscious sedation. The mean (SD) lowest S(p) O(2) was 97 (1.7) % when breathing room air and no volunteer required supplementary oxygen. The mean (SD) maximum effect-site propofol concentration reached was 1.7 (0.4) µg.ml(-1) . The present system was found to be safer than its predecessors, allowing conscious sedation, but preventing over-sedation.

Search for charged Higgs bosons in e+e- collisions at [Formula: see text].

A search is made for charged Higgs bosons predicted by Two-Higgs-Doublet extensions of the Standard Model (2HDM) using electron-positron collision data collected by the OPAL experiment at [Formula: see text], corresponding to an integrated luminosity of approximately 600 pb-1. Charged Higgs bosons are assumed to be pair-produced and to decay into [Formula: see text], τντ or AW±. No signal is observed. Model-independent limits on the charged Higgs-boson production cross section are derived by combining these results with previous searches at lower energies. Under the assumption [Formula: see text], motivated by general 2HDM type II models, excluded areas on the [Formula: see text] plane are presented and charged Higgs bosons are excluded up to a mass of 76.3 GeV at 95 % confidence level, independent of the branching ratio BR(H±â†’τντ ). A scan of the 2HDM type I model parameter space is performed and limits on the Higgs-boson masses [Formula: see text] and mA are presented for different choices of tanß.

Rapid aneuploidy screening with fluorescence in-situ hybridisation: is it a sufficiently robust stand-alone test for prenatal diagnosis?

OBJECTIVES: To assess the clinical utility of fluorescence in-situ hybridisation with chromosomes 13, 18, 21, X and Y as a stand-alone test in detecting chromosomal abnormalities, and the types of chromosomal abnormalities missed. DESIGN: Retrospective analysis. SETTING: A restructured Government hospital in Singapore and an academic hospital in the United States. PARTICIPANTS: Cytogenetic data of prenatal specimens and results of fluorescence in-situ hybridisation of 5883 patients performed between January 2000 and August 2007 were reviewed. RESULTS: Fluorescence in-situ hybridisation detected 558 (9.5%) patients with chromosomal abnormalities. Abnormal ultrasounds (70%) and maternal serum screens (21%) were the most indicative of chromosomal abnormalities. When comparing fluorescence in-situ hybridisation data with karyotype results for the five chromosomes of interest, the sensitivity and specificity were 99.3% and 99.9%, respectively. When comparing fluorescence in-situ hybridisation data with karyotype results for all chromosomes, the sensitivity decreased to 86.8%, whereas the specificity remained at 99.9%. Of 643 cases with karyotype abnormalities, 85 were fluorescence in-situ hybridisation-negative (false negative rate, 13.2%), which included structural rearrangements, chromosome mosaicism, and other trisomies. Despite abnormal ultrasound indications, fluorescence in-situ hybridisation missed 32 cases which included structural rearrangements, mosaicisms, and other trisomies. CONCLUSION: This study does not support fluorescence in-situ hybridisation as a stand-alone test. Institutions supporting fluorescence in-situ hybridisation as a stand-alone test must seriously consider the risks of a missed diagnosis.

The cardiovascular effects of normobaric hyperoxia in patients with heart rate fixed by permanent pacemaker.

To investigate whether the established reductions in heart rate and cardiac output with hyperoxia in humans are primary effects or secondary to increases in systemic vascular resistance, we paced the hearts of nine patients with permanent pacemakers at a fixed rate when breathing either medical air (inspired O(2) fraction 0.21) or oxygen (inspired O(2) fraction 0.80) in a randomised, double-blind fashion. A thoracic bio-impedance machine was used to measure heart rate, stroke volume and blood pressure and calculate cardiac index and systemic vascular resistance index. Oxygen caused no change in cardiac index (p = 0.18), stroke index (p = 0.44) or blood pressure (p = 0.52) but caused a small (5.5%) increase in systemic vascular resistance index (p = 0.03). This suggests that hyperoxia has no direct myocardial depressant effects, but that the changes in cardiac output reported in previous studies are secondary to changes in systemic vascular resistance.

Anatomy of the nasal profile.

There is a lack in the understanding of the variation within the thickness of the soft tissue structures (muscle, skin and fat) overlying the cartilaginous skeleton of the nose and their relationship to the dorsum shape. We examined such relationships by dissecting noses of six adult female and six adult male cadavers, comparing the internal anatomical structures to the external nasal profile. We found that the soft tissue structures differ in thickness along the dorsum and that these differences are individualized. Specifically, continuous presence of subcutaneous fat from root to tip was found in half the sample, one nose had fat only on the tip, another one only on the root, the four others at both positions. The nasalis muscle was identifiable in nine of the 12 noses, transversing the nose in half the sample, and in the remaining three, only the lateral section of the muscle was identified. The superior border of the septal cartilage does not form a linear extension of the profile contour of the nasal bones but angles downwards. The actual profile contour of the dorsum does not follow the profile of the nasal bones or the septal cartilage. These results may influence the current use of nasal guidelines in forensic facial approximation.

Effects of normobaric hyperoxia on haemodynamic parameters of healthy full-term parturients.

Fifteen healthy, full-term women with singleton pregnancies were exposed to an increased F(I)o(2) of 0.4 and their haemodynamic responses measured with a non-invasive transthoracic bio-impedance monitor. There was a mean reduction in cardiac index from 3.18 to 3.03 l x min(-1) x m(-2) (4.7%, p = 0.004). The mean indexed systemic vascular resistance increased from 2049 to 2178 dynes x cm(-5) x m(-2) (5.7%, p = 0.005). There were no significant changes in stroke index, heart rate or mean arterial pressure. This study demonstrates that even a moderate increase in inspired oxygen fraction has significant effects on the cardiovascular system of the term parturient.

The cardiovascular effects of inspired oxygen fraction in anaesthetized patients.

BACKGROUND AND OBJECTIVE: Increased inspired oxygen fractions (FiO2) have significant haemodynamic effects in awake volunteers. We sought to establish whether these effects are also present in anaesthetized patients. METHODS: We prospectively studied 30 ASA I-II patients, 15 in each of a propofol and sevoflurane group. Their haemodynamic responses, awake and anaesthetized, when the FiO2 was changed between 0.3 and 1.0 were measured with a non-invasive transthoracic bio-impedance monitor. RESULTS: While preoxygenating awake patients in both groups the FiO2 was increased from 0.21 to 1.0. This reduced the mean cardiac index (3.38 +/- 0.5 to 3.03 +/- 0.5 L min(-1) m(-2); P < 0.001); reduced the heart rate (HR) (68.1 +/- 10.4 to 62.8 +/- 9.4 beats per minute (bpm); P < 0.001); and reduced the stroke index (50.4 +/- 9.6 to 48.5 +/- 8.6; P = 0.02). It increased the systemic vascular resistance index (2060 +/- 319 to 2220 +/- 382 dyn s(-1) cm(-5) m(-2); P = 0.002); but did not change mean arterial pressure. In the anaesthetized patients, when decreasing the FiO2 from 1.0 to 0.3, mean cardiac index (L min(-1) m(-2) increased (3.06 +/- 0.57 to 3.25 +/- 0.56, P = 0.008 for sevoflurane; 2.76 +/- 0.46 to 2.89 +/- 0.42, P = 0.002 for propofol). The mean HR (bpm) increased (65.1 +/- 7.8 to 69.1 +/- 7.5, P < 0.001 for sevoflurane; 67.5 +/- 11.8 to 72.7 +/- 11.6, P = 0.001 for propofol). The mean systemic vascular resistance (dyn s(-1) cm(-5) m(-2)) decreased (1883 +/- 329 to 1735 +/- 388, P = 0.008 for sevoflurane; 2015 +/- 369 to 1771 +/- 259, P = 0.003 for propofol). Mean arterial pressure (mmHg) decreased (74.8 +/- 8.7 to 71.4 +/- 8.7, P < 0.001 for sevoflurane; 72.1 +/- 8 to 66.5 +/- 6.8, P = 0.002 for propofol). CONCLUSION: O2 has haemodynamic effects in awake and anaesthetized patients. These effects were of overall similar magnitude for patients anaesthetized with propofol and sevoflurane.

Effect-site controlled patient maintained propofol sedation: a volunteer safety study.

Effect-site concentration is a mathematical term related to the clinical effect of a drug. We have designed a patient-maintained sedation system for delivering propofol to the predicted effect-site concentration rather than plasma concentration. To assess its efficacy and safety, 20 healthy volunteers deliberately attempted to over-sedate themselves using the system. The new effect-site concentration driven system delivered sedation successfully, and more rapidly than its predecessor. Fifteen volunteers ended the study when the system automatically reduced the effect-site concentration after 6 min of no button presses despite verbal contact and maintenance of arterial oxygen saturation (at effect-site concentration 1.8-3.8 microg x ml(-1)). Four out of 20 volunteers ended with minor arterial desaturation (lowest 88% at effect-site concentration 2.6-3.4 microg x ml(-1)). One volunteer ended after loss of verbal contact at effect-site concentration 3.4 microg x ml(-1). Further modification of the system's design is necessary before it can be recommended for routine practice.

The effect of normobaric hyperoxia on cardiac index in healthy awake volunteers.

Fifteen healthy volunteers were exposed to a stepwise increase in FIO2 between 0.21 and 1.0, and their haemodynamic responses were measured with a non-invasive transthoracic bio-impedance monitor. There was mean reduction in cardiac index from 3.44 to 3.08 l.min-1.m-2 (10.7%, p < 0.001). The mean reduction in heart rate was from 77.3 to 69.1 beats.min-1 (10.5%, p < 0.001) and the mean systemic vascular index increased from 2062 to 2221 dyne.s-1.cm-5.m-2 (7.7%, p < 0.025). There were no significant changes in stroke index or mean arterial pressure. These changes are similar quantitatively and qualitatively to those previously reported by dye dilution techniques.

The effect of single use laryngoscopy equipment on illumination for tracheal intubation.

We measured the illumination generated by all 30 Macintosh size 3 laryngoscopes in our department with a lux-meter and a standardised laryngoscope holding tube. We found a large range in illumination generated (65-3130 lx). We then measured the effect on the illumination for each laryngoscope by covering the blade with a cover (LaryGard). In every case, the illumination was reduced by the LaryGard, the mean (SD) reduction was 67 (19)%. When we compared the illumination generated by a disposable laryngoscope blade with the same power source, we found that the illumination was reduced less than with the standard Macintosh covered by a LaryGard.

Absence of physiological tolerance to cocaine in pregnant sheep.

OBJECTIVE: To determine whether repetitive administration of cocaine to sheep during pregnancy altered basal hemodynamic states in the mother and fetus, and to determine whether this cocaine exposure would alter subsequent hemodynamic responses to cocaine. METHODS: Cocaine or saline was administered to 16 pregnant sheep daily from day 75 to day 128 of gestation (term = 145 days). At 128 days' gestation, maternal and fetal basal physiological measurements, including organ-specific blood flow in the fetus, were determined. Each experimental and control ewe then received cocaine 2 mg/kg and these physiological parameters were again measured over the next 30 min to determine whether the experimental animals had developed tolerance to the effects of cocaine. RESULTS: No differences were seen in basal physiological parameters between treatment groups. Likewise, following an acute administration of cocaine, physiological parameters in both groups responded in a similar fashion. Fetal hypoxemia occurred in both groups after the ewe received cocaine. In response to hypoxemia, whether it was the animals' first or 53rd exposure to cocaine, fetal cerebral, myocardial and adrenal blood flow increased so that oxygen delivery was unimpaired. CONCLUSIONS: For the cardiovascular parameters measured in this study, we found no tolerance to cocaine in the ewe or fetus. The acute hemodynamic effects of maternal cocaine administration were as severe for animals having received it more than 50 times as for those that received it for the first time.

Walnut polyphenolics inhibit in vitro human plasma and LDL oxidation.

Recent epidemiologic studies have associated nut consumption with a reduced incidence of cardiovascular mortality. However, little is known about the contribution of nut polyphenols to antioxidant and cardiovascular protection. In this investigation, polyphenol-rich extracts from English walnuts (Juglans regia) were studied and compared with ellagic acid for their ability to inhibit in vitro plasma and LDL oxidation, as well as their effects on LDL alpha-tocopherol during oxidative stress. In addition, the Trolox equivalent antioxidant activity (TEAC) was determined and liquid chromatography electrospray detection mass spectrometry (LC-ELSD/MS) analyses of the walnut extracts were performed. 2,2'-Azobis'(2-amidino propane) hydrochloride (AAPH)-induced LDL oxidation was significantly inhibited by 87 and 38% with the highest concentration (1.0 micromol/L) of ellagic acid and walnut extract, respectively. In addition, copper-mediated LDL oxidation was inhibited by 14 and 84% in the presence of ellagic acid and walnut extract, respectively, with a modest, significant LDL alpha-tocopherol sparing effect observed. Plasma thiobarbituric acid reacting substance (TBARS) formation was significantly inhibited by walnut extracts and ellagic acid in a dose-dependent manner, and the extracts exhibited a TEAC value greater than that of alpha-tocopherol. LC-ELSD/MS analysis of the walnut extracts identified ellagic acid monomers, polymeric ellagitannins and other phenolics, principally nonflavonoid compounds. These results demonstrate that walnut polyphenolics are effective inhibitors of in vitro plasma and LDL oxidation. The polyphenolic content of walnuts should be considered when evaluating their antiatherogenic potential.

Ontogeny and localization of the neutral amino acid transporter ASCT1 in rat brain.

ASCT1 is a protein that encodes System ASC, a sodium-dependent amino acid transport activity that transports primarily zwitterionic amino acids at physiological pH. ASCT1 has a 39-44% identity to the EAAT family of glutamate transporters. At extracellular pH values below 7.4, ASCT1 shifts substrate specificity to transport anionic amino acids. In this study we have examined the location of the ASCT1 transporter by immunohistochemistry in the developing rat brain. In addition, we have examined the cellular localization of ASCT1 in glial and neuronal cultures. The presence of ASCT1 immunoreactivity (ASCT1ir) in the developing brain was detectable as early as 14 days of gestation. At the cellular level, ASCT1ir was prominent in hippocampal pyramidal and dentate granule neurons. In the cerebellum, Purkinje cells and their dendrites were intensely labeled, whereas the granule and molecular layers were moderately labeled. In the cerebral cortex, neuronal cell bodies in all lamina and scattered astrocytes showed intense ASCT1ir. Double labeling experiments in vitro confirmed that ASCT1 was localized to both glia and neurons. These data illustrate that the rat ASCT1 transporter is expressed in the developing brain at levels equivalent to those observed in adult tissue. In addition, the expression and localization of ASCT1 are consistent with its possible role in pathophysiological processes that involve glutamate toxicity.

Elimination of cocaine by pregnant sheep following single or multiple exposures.

To test the hypothesis that chronic exposure to cocaine would alter drug elimination in pregnant and fetal sheep compared to a single exposure, we administered intravenous cocaine HCl to 8 pregnant sheep daily as a bolus, followed by a 2-h infusion beginning at gestational age 75 days. Eight additional animals received an equivalent volume of saline. Three days after maternal and fetal catheter placement on day 125, ewes in both groups received cocaine HCl, 2 mg/kg, as a bolus. Maternal and fetal plasma samples were serially obtained and analyzed for cocaine and benzoylecognine. Cocaine half-life in the ewes and fetuses exposed to cocaine was no different from that in animals exposed to saline. We conclude that cocaine is rapidly metabolized in pregnant sheep and that chronic administration does not alter drug clearance.

Internet use among college students: an exploratory study.

The author and associates surveyed 1,300 college students in classrooms at eight academic institutions to identify how the students' use of the Internet has affected their social or academic lives. Although the typical Internet-using student uses the Internet for 100 minutes per day, a small group of students use the Internet to a degree that interferes with other aspects of their lives. Most of them are men and are found among the hard science academic majors. Some ideas for dealing with this problem are suggested.