Functional characterization of the Aspergillus nidulans glucosylceramide pathway reveals that LCB Δ8-desaturation and C9-methylation are relevant to filamentous growth, lipid raft localization and Psd1 defensin activity.

C8-desaturated and C9-methylated glucosylceramide (GlcCer) is a fungal-specific sphingolipid that plays an important role in the growth and virulence of many species. In this work, we investigated the contribution of Aspergillus nidulans sphingolipid Δ8-desaturase (SdeA), sphingolipid C9-methyltransferases (SmtA/SmtB) and glucosylceramide synthase (GcsA) to fungal phenotypes, sensitivity to Psd1 defensin and Galleria mellonella virulence. We showed that ΔsdeA accumulated C8-saturated and unmethylated GlcCer, while gcsA deletion impaired GlcCer synthesis. Although increased levels of unmethylated GlcCer were observed in smtA and smtB mutants, ΔsmtA and wild-type cells showed a similar 9,Me-GlcCer content, reduced by 50% in the smtB disruptant. The compromised 9,Me-GlcCer production in the ΔsmtB strain was not accompanied by reduced filamentation or defects in cell polarity. When combined with the smtA deletion, smtB repression significantly increased unmethylated GlcCer levels and compromised filamentous growth. Furthermore, sdeA and gcsA mutants displayed growth defects and raft mislocalization, which were accompanied by reduced neutral lipids levels and attenuated G. mellonella virulence in the ΔgcsA strain. Finally, ΔsdeA and ΔgcsA showed increased resistance to Psd1, suggesting that GlcCer synthesis and fungal sphingoid base structure specificities are relevant not only to differentiation but also to proper recognition by this antifungal defensin.

Combination of heterogeneous EEG feature extraction methods and stacked sequential learning for sleep stage classification.

This work proposes a methodology for sleep stage classification based on two main approaches: the combination of features extracted from electroencephalogram (EEG) signal by different extraction methods, and the use of stacked sequential learning to incorporate predicted information from nearby sleep stages in the final classifier. The feature extraction methods used in this work include three representative ways of extracting information from EEG signals: Hjorth features, wavelet transformation and symbolic representation. Feature selection was then used to evaluate the relevance of individual features from this set of methods. Stacked sequential learning uses a second-layer classifier to improve the classification by using previous and posterior first-layer predicted stages as additional features providing information to the model. Results show that both approaches enhance the sleep stage classification accuracy rate, thus leading to a closer approximation to the experts' opinion.

A limited approach to the jugular bulb: anatomical considerations in a rare jugular foramen tumour.

We report a case of a rare schwannoma of the jugular foramen and removed it by a limited transjugular approach. A limited surgical approach was performed for removal of the tumour, with preservation of surrounding structures. A thorough understanding of the anatomy of the region is necessary for our limited transjugular approach. The schwannoma was successfully removed. Through a detailed understanding of the anatomy of the region and adequate classification of the tumour, a limited surgical approach is not only possible, but preferable.

Medicolegal significance of asymmetrical hearing loss in cases of industrial noise exposure.

OBJECTIVE: In Australia, the current guidelines for evaluation of noise-induced hearing loss suggest that, in cases of asymmetrical loss, 'the worse ear be equated to the better ear' for purposes of compensation. This study aimed to establish that such a method was prejudicial to the worker (i.e. the plaintiff). In consideration of the legal duty 'to co-construct the ideas of truth and the ideas of justice in the context of legal proceedings', our study objectives were (1) to document the incidence of asymmetrical hearing loss in compensation cases seen in our practice, and (2) to provide a reasoned argument for inclusion of the same for compensation considerations. STUDY DESIGN: Open, retrospective, clinical study. SETTING: Australian plaintiffs with asymmetrical hearing loss (who comprise a significant percentage of industrial hearing loss legal cases) may be excluded from full consideration of their hearing loss as a result of the current guidelines. In contrast to the process of medical diagnosis and treatment, it appeared that the application of accepted probability standards within the legal process may permit inclusion of such clients' hearing loss in compensation considerations. METHODS: This study included 208 consecutive clients referred by legal practitioners for assessment of hearing loss for compensation purposes. RESULTS AND CONCLUSION: A total of 22.6 per cent of clients (47 of 208) had asymmetrical hearing loss, with the left side having the greater loss in 60 per cent of cases. We believe that asymmetrical hearing loss should be included in compensation considerations, both on medical and legal grounds.

Classification of the maxillary sinus according to area of the medial antral wall: a comparison of two ethnic groups.

OBJECTIVES: This study is an anatomical study designed to benefit surgeons working in the region of the maxillary sinus. This paper investigates ethnic and gender variations in the shape of the maxillary sinus in dried crania from the Raymond Dart collection of human skeletons. The paper claims that an estimate of the area of the medial antral wall of the maxillary sinus is one of the best ethnic/gender group predictors. METHODOLOGY: Helical, multislice computed tomography was performed using 1mm coronal slices length, depth, width and volume measurements for each sinus were taken. Classification by shape and estimated area of medial wall was attempted. RESULTS: Shape classification was found to be unsuccessful whilst medial wall classification into ethnic/gender groupings gave encouraging results. CONCLUSION: The area of the medial wall is related to ethnic/gender groups.

The snake venom metalloproteinase BaP1 induces joint hypernociception through TNF-alpha and PGE2-dependent mechanisms.

BACKGROUND AND PURPOSE: Matrix metalloproteinases (MMPs) have been implicated in joint tissue destruction in arthritis. However, MMPs have not been assigned a role in joint pain. We investigated the ability of BaP1, a metalloproteinase from Bothrops asper snake venom, with structural homology to MMPs, to induce joint hypernociception. EXPERIMENTAL APPROACH: Animals received intra-articular (i.art.) BaP1. Hypernociception was assessed using the rat-knee joint articular incapacitation test. Cell influx, prostaglandin E(2) (PGE(2)), and TNF-alpha levels were assessed in joint exudates following BaP1 injection. KEY RESULTS: BaP1 (5 microg per joint) provoked hypernociception between 1 and 6 h after i.art. injection. Cell influx, mostly neutrophils, was maximal 3 h after BaP1 i.art. injection. BaP1 also led to increase in PGE(2) and TNF-alpha levels in the joint exudates. Pretreatment with either indomethacin (4 mg.kg(-1) i.p.) or with an anti-TNF-alpha antiserum (i.art.) significantly inhibited both BaP1-induced joint hypernociception and cell influx. In isolated rat peritoneal macrophages, BaP1 increased cyclooxygenase (COX)-2 expression, while not altering that of COX-1. CONCLUSIONS AND IMPLICATIONS: This is the first demonstration that a metalloproteinase promotes joint hypernociception. This effect involves local release of PGE(2) and TNF-alpha. BaP1-induced increase in PGE(2) is associated to increased COX-2 expression in macrophages. Blocking PGE(2) or TNF-alpha inhibits BaP1-induced hypernociception. In addition to unravelling a hitherto unknown mechanism whereby TNF blockade provides analgesia in arthritis, the data show, for the first time that MMPs are involved in inflammatory joint hypernociception and induce COX-2 expression.

Neutrophils do not contribute to local tissue damage, but play a key role in skeletal muscle regeneration, in mice injected with Bothrops asper snake venom.

Local tissue damage induced by crotaline snake venoms includes edema, myonecrosis, hemorrhage, and an inflammatory response associated with a prominent cellular infiltrate. The role of neutrophils in the local tissue damage induced by Bothrops asper snake venom and by myotoxin I, a phospholipase A2 isolated from this venom, was investigated. Male Swiss mice were pretreated with either an antimouse granulocyte rat monoclonal immunoglobulin G (IgG) antibody or with isotype-matched control antibody. No significant differences in these local effects were observed between mice pretreated with antigranulocyte antibodies and those receiving control IgG. Moreover, myotoxicity induced by B. asper myotoxin I was similar in neutrophil-depleted and control mice. The role of neutrophils in the process of skeletal muscle regeneration was also assessed. Muscle regeneration was assessed by quantifying the muscle levels of creatine kinase and by morphometric histological analysis of the area comprised by regenerating cells in damaged regions of skeletal muscle. Mice depleted of neutrophils and then injected with B. asper venom showed a more deficient regenerative response than mice pretreated with control IgG. Moreover, a drastic difference in the regenerative response was observed in mice injected with myotoxin I, because animals pretreated with control IgG showed a successful regeneration, whereas those depleted of neutrophils had abundant areas of necrotic tissue that had not been removed 7 days after injection, associated with reduced contents of creatine kinase. It is concluded that (1) neutrophils do not play a significant role in the acute local pathological alterations induced by the venom of B. asper, and (2) neutrophils play a prominent role in the process of skeletal muscle regeneration after injection of B. asper venom and myotoxin I, probably related to the phagocytosis of necrotic material and the recruitment of other inflammatory cells, two events directly associated with a successful muscle regenerative response.

Pyoderma gangrenosum or leukaemia cutis?

We report a case of atypical bullous pyoderma gangrenosum associated with acute myeloid leukaemia in which we found atypical myeloid cells within the skin lesion. Although there have been many reported cases of leukaemia-associated pyoderma gangrenosum, the finding of myeloblasts in the skin has rarely been described.

Molecular modelling and 1H-NMR: ultimate tools for the investigation of tolbutamide: beta-cyclodextrin and tolbutamide: hydroxypropyl-beta-cyclodextrin complexes.

A structural study of the inclusion compound of tolbutamide (TBM) with beta-cyclodextrin (beta-CD) and hydroxypropyl-beta-cyclodextrin (HP-beta-CD) was attempted by means of 1H-nuclear magnetic resonance (1H-NMR) experiments and computer molecular modelling. To establish the stoichiometry and stability constant of the beta-CD:TBM complex, the continuous variation method was used. The presence of true inclusion complexes between TBM and beta-CD or HP-beta-CD in solution was clearly evidenced by the 1H-NMR technique. Changes in chemical shifts of H-3 and H-5 protons, located inside the CD cavity, associated with variations in the chemical shifts of TBM aromatic protons provided clear evidence of inclusion complexation, suggesting that the phenyl moiety of the drug molecule was included in the hydrophobic cavity of CDs. This view was further supported by the observation of intermolecular NOEs between TBM and beta-CD and by the aid of a molecular modelling program, which established the most probable structure of the complex. The molecular graphic computation confirmed that the minimum energy, positioning TBM relative to beta-CD, occurs when the aromatic ring of TBM is included within the beta-CD cavity by its wider side, leaving the aliphatic chain externally, which is in good agreement with the results of 1H-NMR studies.

Degradable dextran microspheres for the controlled release of liposomes.

A novel delivery concept based on the encapsulation of liposomes in biodegradable dextran microspheres was developed. The microspheres were prepared using a two-phase system, consisting of water/poly(ethylene glycol), and water/methacrylated dextran. Liposomes were encapsulated almost quantitatively and in their intact form, and were released with full preservation of their integrity. The effects of microsphere water content, degree of methacrylate substitution, and type of dextran derivative used on the release rate were investigated. The release of the liposomes from the dextran microspheres was fully controlled by the degradation rate of the spheres. This resulted, after a lag time, in a pulsed release of the liposomes from relatively rapidly degrading microspheres. On the other hand, slower degrading microspheres resulted in sustained release of liposomes over 100 days. The degradation rate of the dextran microspheres, in turn, depended on the water content, the degree of methacrylate substitution, and type of hydrolytically sensitive spacer present in the cross-links.

Controlled release of liposomes from biodegradable dextran microspheres: a novel delivery concept.

PURPOSE: To design liposome-loaded microspheres, which release the liposomes in a time-controlled manner and in intact form. METHODS: Liposomes were encapsulated in biodegradable dextran-based microspheres, which were prepared using an aqueous two phase system consisting of poly(ethylene glycol) and methacrylated dextran. The effects of liposome size and membrane fluidity, microsphere water content, degree of methacrylate substitution, and type of dextran derivative used, on encapsulation efficiency, release, and integrity of the liposomes were investigated. RESULTS: Liposomes were entrapped in dextran-based microspheres quantitatively and with full preservation of their integrity. Liposomes with a low, as well as with a high membrane fluidity, were released from the microspheres in their intact form and with preservation of their size. Release kinetics depended only on the degradation rate of the microspheres. For rapidly degrading systems, pulsed release was observed and the time after which the pulse occurred (from 5 until 25 days) could be tailored by the gel characteristics such as initial water content, degree of methacrylate substitution, and type of hydrolytically sensitive spacer present in the cross-links. This delay time was not dependent on the size of the liposomes in the range studied (0.1-0.2 microm). Microspheres which degraded more slowly showed, after a certain delay time, sustained release of the liposomes extended up to 100 days. CONCLUSIONS: A novel drug delivery concept based on the encapsulation of liposomes in biodegradable dextran-based microspheres was designed. The system released the liposomes in intact form in a controlled way after a prolonged period of time.

Necrotizing fasciitis secondary to group A streptococcus. Morbidity and mortality still high.

OBJECTIVE: To update physicians on Group A streptococcal necrotizing fasciitis, including current methods of diagnosis and treatment. QUALITY OF EVIDENCE: Current literature (1990-1998) was searched via MEDLINE using the MeSH headings necrotizing fasciitis, toxic shock syndrome, and Streptococcus. Articles were selected based on clinical relevance and design. Most were case reports, case series, or population-based surveys. There were no randomized controlled trials. MAIN MESSAGE: The hallmark of clinical diagnosis of necrotizing fasciitis is pain out of proportion to physical findings. Suspicion of underlying soft tissue infection should prompt urgent surgical examination. Therapy consists of definitive excisional surgical debridement in conjunction with high-dose intravenous penicillin G and clindamicin. Risk factors for mortality include advanced age, underlying illness, hypotension, and bacteremia. CONCLUSION: Necrotizing soft tissue infections due to Group A streptococcus might be increasing in frequency and aggression. Overall mortality remains high (20% to 34% in larger series). Clinical diagnosis requires a high level of suspicion and should prompt urgent surgical referral.

Frequent users of the emergency department: a program to improve care and reduce visits.

The authors describe a case-management program for frequent users of the emergency department. The study had a single-subject design, with evaluation for each patient of the number of visits to the emergency department for a 12-month period before referral to the program and a similar period after implementation of an individualized care plan. Referrals were made on the basis of 2 or more of the following criteria: chronic medical condition, complex medical condition, drug-seeking behaviour, violent behaviour and abusive behaviour. A multidisciplinary team developed the individualized care plans. Twenty-four patients agreed to participate. For the 12-month period before their referral, these patients accounted for a total of 616 (median 26.5) visits to the emergency department; for a similar period after implementation of the care plans, they accounted for 175 (median 6.5) visits. The difficult-case management program appeared to be effective in reducing the total number of visits to the emergency department during the study period and in improving the care for these patients.

Violence in the emergency department: a survey of health care workers.

BACKGROUND: Violence in the workplace is an ill-defined and underreported concern for health care workers. The objectives of this study were to examine perceived levels of violence in the emergency department, to obtain health care workers' definitions of violence, to determine the effect of violence on health care workers and to determine coping mechanisms and potential preventive strategies. METHODS: A retrospective written survey of all 163 emergency department employees working in 1996 at an urban inner-city tertiary care centre in Vancouver. The survey elicited demographic information, personal definition of violence, severity of violence, degree of stress as a result of violence and estimate of the number of encounters with violence in the workplace in 1996. The authors examined the effects of violence on job performance and job satisfaction, and reviewed coping and potential preventive strategies. RESULTS: Of the 163 staff, 106 (65%) completed the survey. A total of 68% (70/103) reported an increased frequency of violence over time, and 60% (64/106) reported an increased severity. Most of the respondents felt that violence included witnessing verbal abuse (76%) and witnessing physical threats or assaults (86%). Sixty respondents (57%) were physically assaulted in 1996. Overall, 51 respondents (48%) reported impaired job performance for the rest of the shift or the rest of the week after an incident of violence. Seventy-seven respondents (73%) were afraid of patients as a result of violence, almost half (49%) hid their identities from patients, and 78 (74%) had reduced job satisfaction. Over one-fourth of the respondents (27/101) took days off because of violence. Of the 18 respondents no longer working in the emergency department, 12 (67%) reported that they had left the job at least partly owing to violence. Twenty-four-hour security and a workshop on violence prevention strategies were felt to be the most useful potential interventions. Physical exercise, sleep and the company of family and friends were the most frequent coping strategies. INTERPRETATION: Violence in the emergency department is frequent and has a substantial effect on staff well-being and job satisfaction.

How accurately do we estimate patients' weight in emergency departments?

OBJECTIVE: To assess the accuracy of estimates of patients' weight made by physicians, nurses, and patients themselves in emergency departments. DESIGN: Observational prospective study. SETTING: Tertiary referral centre in Vancouver, BC. PARTICIPANTS: Eleven attending physicians, 26 nurses, and a convenience sample of 117 patients. INTERVENTIONS: Patients themselves, attending physicians, and nurses independently estimated the weight of 117 patients. An investigator weighed each patient. MAIN OUTCOME MEASURES: Mean error was determined by subtracting actual weight from estimated weight and dividing by actual weight; 95% confidence intervals (CI) were calculated. RESULTS: Mean error in estimates was 3.1% (95% CI 2.7 to 3.5) for patients, 8.4% for nurses (CI 7.6 to 9.2), and 8.1% (CI 7.1 to 9.1) for physicians. Weight was estimated within 5% of actual weight by 32% of nurses, 39% of physicians, and 82% of patients. Weight was estimated within 10% of actual weight by 66% of nurses, 66% of physicians, and 97% of patients. Estimates out by more than 15% were made by 11% of nurses, 16% of physicians, and 1% of patients. CONCLUSIONS: Patient estimates were most accurate. Physician and nurse estimates were unreliable.

How reliable is emergency department triage?

STUDY OBJECTIVE: To measure interrater and intrarater agreement for an emergency department triage system. METHODS: A 2-phase experimental study was conducted using previously described in-person scripted encounters with emergency nurses who perform patient triage and attending emergency physicians at a tertiary referral center. Standardized patient scenarios were presented twice over 6 weeks. Participants rated severity for each patient using a 5-tier triage system (nurses only) and estimated the probability of hospital admission, the most appropriate time frame to physician evaluation (5 choices, from "Immediate" to "More than 24 hours"), the need for a monitored ED bed, and the need for diagnostic services. Interrater agreement was measured by a coefficient of agreement for multiple raters and multiple categories. RESULTS: Of the 37 participants (fewer than 90% of those eligible), 19 (51%) completed both phases (12 nurses, 7 physicians). Four (33%) of the nurses assigned the same severity ratings for the 5 cases in phase 2 as they did in phase 1. Intrarater agreement among the 12 nurses rating triage severity was.757. Interrater agreement of nurses and physicians was substantial regarding need for ED monitoring, and moderate to substantial for other triage assessments. CONCLUSION: There was general agreement in interrater assessment of triage classification. Continued work is necessary to more fully delineate areas of variation.

Inconsistency of emergency department triage. Emergency Department Operations Research Working Group.

STUDY OBJECTIVE: To measure the interrater and intrarater agreement of existing emergency department triage systems. METHODS: This 2-phase experimental study of triage nurses' and EMTs ratings for 5 scripted patient scenarios used in-person interviews and follow-up written surveys. RESULTS: Eighty-seven participants (> 90% of those eligible) with 55 (63%) completed both phases of the study. Interrater agreement on triage category was poor (kappa = .347 overall). Only 13 of 55 (24%) participants rated the 5 cases the same severity in both phases; Kendall correlation (iota-B) comparing phases 1 and 2 varied from .145 to .554. Estimates of admission probability varied widely. Estimates of the appropriate time to physician evaluation (from immediate to 24 hours) was often incongruous with severity ratings (e.g., 54% of those participants rating a case the lowest severity recommended evaluation within 8 hours). There was good agreement on estimated need for an ED monitored bed or diagnostic studies. CONCLUSION: Triage assessments (both interrater and intrarater) by experienced personnel are inconsistent using these 5 standardized patient scenarios. These results challenge the reliability of current ED triage practice.