Cryo-EM structure determination of small therapeutic protein targets at 3 Å-resolution using a rigid imaging scaffold

Cryoelectron microscopy (Cryo-EM) has enabled structural determination of proteins larger than about 50 kDa, including many intractable by any other method, but it has largely failed for smaller proteins. Here, we obtain structures of small proteins by binding them to a rigid molecular scaffold based on a designed protein cage, revealing atomic details at resolutions reaching 2.9 Å. We apply this system to the key cancer signaling protein KRAS (19 kDa in size), obtaining four structures of oncogenic mutational variants by cryo-EM. Importantly, a structure for the key G12C mutant bound to an inhibitor drug (AMG510) reveals significant conformational differences compared to prior data in the crystalline state. The findings highlight the promise of cryo-EM scaffolds for advancing the design of drug molecules against small therapeutic protein targets in cancer and other human diseases.

Mapping the DNA-Binding Motif of Scabin Toxin, a Guanine Modifying Enzyme from Streptomyces scabies

Scabin is a mono-ADP-ribosyltransferase toxin/enzyme and possible virulence factor produced by the agriculture pathogen, Streptomyces scabies. Recently, molecular dynamic approaches and MD simulations revealed its interaction with both NAD⁺ and DNA substrates. An Essential Dynamics Analysis identified a crab-claw-like mechanism, including coupled changes in the exposed motifs, and the R_β1-R_La-N_Lc-STT_β2-W_PN-W_ARTT-(QxE)_ARTT sequence motif was proposed as a catalytic signature of the Pierisin family of DNA-acting toxins. A new fluorescence assay was devised to measure the kinetics for both RNA and DNA substrates. Several protein variants were prepared to probe the Scabin-NAD-DNA molecular model and to reveal the reaction mechanism for the transfer of ADP-ribose to the guanine base in the DNA substrate. The results revealed that there are several lysine and arginine residues in Scabin that are important for binding the DNA substrate; also, key residues such as Asn110 in the mechanism of ADP-ribose transfer to the guanine base were identified. The DNA-binding residues are shared with ScARP from Streptomyces coelicolor but are not conserved with Pierisin-1, suggesting that the modification of guanine bases by ADP-ribosyltransferases is divergent even in the Pierisin family.

Dynamics of Scabin toxin. A proposal for the binding mode of the DNA substrate

Scabin is a mono-ADP-ribosyltransferase enzyme and is a putative virulence factor produced by the plant pathogen, Streptomyces scabies. Previously, crystal structures of Scabin were solved in the presence and absence of substrate analogues and inhibitors. Herein, experimental (hydrogen-deuterium exchange), simulated (molecular dynamics), and theoretical (Gaussian Network Modeling) approaches were systematically applied to study the dynamics of apo-Scabin in the context of a Scabin·NAD⁺·DNA model. MD simulations revealed that the apo-Scabin solution conformation correlates well with the X-ray crystal structure, beyond the conformation of the exposed, mobile regions. In turn, the MD fluctuations correspond with the crystallographic B-factors, with the fluctuations derived from a Gaussian network model, and with the experimental H/D exchange rates. An Essential Dynamics Analysis identified the dynamic aspects of the toxin as a crab-claw-like mechanism of two topological domains, along with coupled deformations of exposed motifs. The “crab-claw” movement resembles the motion of C3-like toxins and emerges as a property of the central β scaffold of catalytic single domain toxins. The exposure and high mobility of the cis side motifs in the Scabin β-core suggest involvement in DNA substrate binding. A ternary Scabin·NAD⁺·DNA model was produced via an independent docking methodology, where the intermolecular interactions correspond to the region of high mobility identified by dynamics analyses and agree with binding and kinetic data reported for wild-type and Scabin variants. Based on data for the Pierisin-like toxin group, the sequence motif R_β1–R_La–N_Lc–STT_β2–W_PN–W_ARTT–(QxE)_ARTT emerges as a catalytic signature involved in the enzymatic activity of these DNA-acting toxins. However, these results also show that Scabin possesses a unique DNA-binding motif within the Pierisin-like toxin group.

Cross-sectional Analysis of the Standards of Consent Applied to Anaesthesia in Ireland: Are Anaesthetists Aware of their Legal and Ethical Obligations?

Consent to a medical intervention has legally and ethically evolved to a process prioritising autonomy and patient-led decision-making. This cross-sectional analysis investigated Irish anaesthetists' practices of taking consent. Following ethical approval, trainees and fellows of the College of Anaesthetists of Ireland were invited to participate in a 33 question online survey. One hundred and sixty responses (11.8%) were received, an equal number coming from consultants and trainees. The majority (93.7%) worked in a teaching hospital. Fifteen percent said their department had guidelines on obtaining consent for anaesthesia, but only 4.5% said their department used a separate consent form. Most (63.8%) do not usually document consent. A significant number rarely (21.8%) or never (27.8%) explained risks to patients. Lack of time was identified as the most frequent barrier (77.6%), with just under half first meeting the patient in the theatre holding-bay or the anaesthetic room. Forty-one percent felt the ultimate decision regarding which anaesthetic technique is employed should usually lie with the anaesthetist alone. These results suggest a wide variation in the practice of obtaining consent for anaesthesia. Less than half deemed their practice to be adequate in this regard, while 50% were concerned about litigation stemming from inadequate consent.

Scabin, a Novel DNA-acting ADP-ribosyltransferase from Streptomyces scabies

A bioinformatics strategy was used to identify Scabin, a novel DNA-targeting enzyme from the plant pathogen 87.22 strain of Streptomyces scabies Scabin shares nearly 40% sequence identity with the Pierisin family of mono-ADP-ribosyltransferase toxins. Scabin was purified to homogeneity as a 22-kDa single-domain enzyme and was shown to possess high NAD(+)-glycohydrolase (Km (NAD) = 68 ± 3 μm; kcat = 94 ± 2 min(-1)) activity with an RSQXE motif; it was also shown to target deoxyguanosine and showed sigmoidal enzyme kinetics (K0.5(deoxyguanosine) = 302 ± 12 μm; kcat = 14 min(-1)). Mass spectrometry analysis revealed that Scabin labels the exocyclic amino group on guanine bases in either single-stranded or double-stranded DNA. Several small molecule inhibitors were identified, and the most potent compounds were found to inhibit the enzyme activity with Ki values ranging from 3 to 24 μm PJ34, a well known inhibitor of poly-ADP-ribosyltransferases, was shown to be the most potent inhibitor of Scabin. Scabin was crystallized, representing the first structure of a DNA-targeting mono-ADP-ribosyltransferase enzyme; the structures of the apo-form (1.45 Å) and with two inhibitors (P6-E, 1.4 Å; PJ34, 1.6 Å) were solved. These x-ray structures are also the first high resolution structures of the Pierisin subgroup of the mono-ADP-ribosyltransferase toxin family. A model of Scabin with its DNA substrate is also proposed.

Frequency and prognostic significance of p16(INK4A) protein overexpression and transcriptionally active human papillomavirus infection in laryngeal squamous cell carcinoma

Background:

Human papillomavirus (HPV) infection is a powerful prognostic biomarker in a subset of head and neck squamous cell carcinomas, specifically oropharyngeal cancers. However, the role of HPV in non-oropharyngeal sites, such as the larynx, remains unconfirmed.

Methods:

We evaluated a cohort of 324 laryngeal squamous cell carcinoma (LSCC) patients for the expression of p16^INK4A (p16) protein by immunohistochemistry (IHC) and for high-risk HPV E6 and E7 mRNA transcripts by RNA in situ hybridisation (ISH). p16 expression and HPV status were correlated with clinicopathological features and outcomes.

Results:

Of 307 patients assessable for p16 IHC, 20 (6.5%) were p16 positive. Females and node-positive patients were more likely to be p16 positive (P<0.05). There were no other significant clinical or demographic differences between p16-positive and -negative cases. There was no difference in overall survival (OS) between p16-positive and -negative patients with 2-year survival of 79% in each group (HR=0.83, 95% CI 0.36–1.89, P=0.65). There was no statistically significant difference in failure-free survival (FFS) with 2-year FFS of 79% and 66% for p16-positive and -negative patients, respectively (HR=0.60, 95% CI 0.26–1.36, P=0.22). Only seven cases were found to be HPV RNA ISH positive, all of which were p16 IHC positive. There was no statistically significant difference in OS between patients with HPV RNA ISH-positive tumours compared with -negative tumours with 2-year survival of 86% and 71%, respectively (HR=0.76, 95% CI 0.23–2.5, P=0.65). The 2-year FFS was 86% and 59%, respectively (HR=0.62, 95% CI 0.19–2.03, P=0.43).

Conclusions:

p16 overexpression is infrequent in LSCC and the proportion of cases with high-risk HPV transcripts is even lower. There are no statistically significant correlations between p16 IHC or HPV RNA ISH status and OS or disease outcomes.

Adherence to abiraterone among the first 86 recipients after release in Saskatchewan

Metastatic castration-resistant prostate cancer is now commonly treated with abiraterone, an orally administered chronic medication. Although abiraterone has certain advantages over docetaxel-based therapy, patients are now responsible for ensuring optimal adherence to their medication. To our knowledge, adherence to abiraterone in a real-world setting has never been described. The objective of the present study was to measure adherence to abiraterone among the first patients to receive the drug in Saskatchewan. Electronic pharmacy claims were obtained from the Saskatchewan Cancer Agency after removal of patient names and identifiers. All patients with at least 1 dispensation for abiraterone between August 2011 and October 2013 were eligible. The primary endpoint was the percentage of patients achieving optimal adherence at 6 months, defined as a medication possession ratio (mpr) of 80% or better. During the study period, 141 patients received abiraterone, among whom 86 could be followed for at least 6 months. Optimal adherence was achieved in 82.6% of patients (71 of 86) at 6 months, with 79.1% achieving a mpr of at least 90%. Of patients with available follow-up to 1 year, 81.6% (31 of 38) maintained optimal adherence during the entire period.

Medical manslaughter

On November 29, 2011 Dr Conrad Murray was sentenced to four years in prison after being convicted of the involuntary manslaughter of Michael Jackson. Expert witness statements indicated that Murray's actions were an "extreme departure from the standard of care", particularly with regard to (1) inappropriately treating insomnia with a surgical anaesthetic (propofol); (2) failing to acquire sufficiently informed consent; (3) administering propofol without the necessary monitoring equipment; (4) delaying contacting the emergency services; and (5) making ineffective resuscitation efforts. Further medical evidence argued that Murray's care of Jackson contained "17 egregious violations", defined as acts that posed a foreseeable danger to the patient's life. These deficiencies, it was stated, constituted gross negligence. Such events might seem remote from daily medical practice in Ireland. However, medical errors resulting in patient death are reported to be unfortunately frequent, even if such fatalities are rarely as dramatic, or as public, as that of Michael Jackson. Medical care is not necessarily straightforward, and any treatment outcome is dependent on clinician skill, the nature of the intervention, and on the pathological condition of the patient. Regardless of these latter two factors, a poor outcome still may occur through physician omissions or the commission of errors or violations. Merry and McCall Smith distinguish between errors and violations on the following basis: (1) errors are not deliberate, and result in unintentional actions and consequences; (2) violations, on the other hand, entail a deliberate deviation from accepted rules or norms. It was alleged that much of Dr Murray's professional conduct in this case fell into the latter category.

Non-obese diabetic-recombination activating gene-1 (NOD-Rag1 null) interleukin (IL)-2 receptor common gamma chain (IL2r gamma null) null mice: a radioresistant model for human lymphohaematopoietic engraftment

Immunodeficient hosts engrafted with human lymphohaematopoietic cells hold great promise as a preclinical bridge for understanding human haematopoiesis and immunity. We now describe a new immunodeficient radioresistant non-obese diabetic mice (NOD) stock based on targeted mutations in the recombination activating gene-1 (Rag1(null)) and interleukin (IL)-2 receptor common gamma chain (IL2rgamma(null)), and compare its ability to support lymphohaematopoietic cell engraftment with that achieved in radiosensitive NOD.CB17-Prkdc(scid) (NOD-Prkdc(scid)) IL2rgamma(null) mice. We observed that immunodeficient NOD-Rag1(null) IL2rgamma(null) mice tolerated much higher levels of irradiation conditioning than did NOD-Prkdc(scid) IL2rgamma(null) mice. High levels of human cord blood stem cell engraftment were observed in both stocks of irradiation-conditioned adult mice, leading to multi-lineage haematopoietic cell populations and a complete repertoire of human immune cells, including human T cells. Human peripheral blood mononuclear cells also engrafted at high levels in unconditioned adult mice of each stock. These data document that Rag1(null) and scid stocks of immunodeficient NOD mice harbouring the IL2rgamma(null) mutation support similar levels of human lymphohaematopoietic cell engraftment. NOD-Rag1(null) IL2rgamma(null) mice will be an important new model for human lymphohaematopoietic cell engraftment studies that require radioresistant hosts.

The Banff 2007 working classification of skin-containing composite tissue allograft pathology

Composite tissue allotransplantation (CTA) is a recently introduced option for limb replacement and reconstruction of tissue defects. As with other allografts, CTA can undergo immune-mediated rejection; therefore standardized criteria are required for characterizing and reporting severity and types of rejection. This article documents the conclusions of a symposium on CTA rejection held at the Ninth Banff Conference on Allograft Pathology in La-Coruna, Spain, on 26 June 2007, and proposes a working classification, the Banff CTA-07, for the categorization of CTA rejection. This classification was derived from a consensus discussion session attended by the first authors of three published classification systems, pathologists and researchers from international centers where clinical CTA has been performed. It was open to all attendees to the Banff conference. To the extent possible, the format followed the established National Institutes of Health (NIH) guidelines on Consensus Development Programs. By consensus, the defining features to diagnose acute skin rejection include inflammatory cell infiltration with involvement of epidermis and/or adnexal structures, epithelial apoptosis, dyskeratosis and necrosis. Five grades of severity of rejection are defined. This classification refines proposed schemas, represents international consensus on this topic, and establishes a working collective classification system for CTA reporting of rejection in skin-containing CTAs.

Development of a novel continuous culture device for experimental evolution of bacterial populations

The availability of a robust and reliable continuous culture apparatus that eliminates wall growth problems would lead to many applications in the microbial field, including allowing genetically engineered strains to recover high fitness, improving biodegradation strains, and predicting likely antibiotic resistance mechanisms. We describe the design and implementation of a novel automated continuous culture machine that can be used both in time-dependent mode (similar to a chemostat) and turbidostat modes, in which wall growth is circumvented through the use of a long, variably divisible tube of growth medium. This tube can be restricted with clamps to create a mobile growth chamber region in which static portions of the tube and the associated medium are replaced together at equal rates. To functionally test the device as a tool for re-adaptation of engineered strains, we evolved a strain carrying a highly deleterious deletion of Elongation Factor P, a gene involved in translation. In 200 generations over 2 weeks of dilution cycles, the evolved strain improved in generation time by a factor of three, with no contaminations and easy manipulation.

Bevacizumab: Analysis of clinical benefit in females across trials in colorectal cancer and non-small cell lung cancer

7634

Background: Bevacizumab (Bv) has demonstrated significant improvement in overall survival (OS) in randomized trials in first- and second-line (FL and SL) metastatic CRC (mCRC), FL NSCLC, and progression-free survival (PFS) in metastatic breast cancer (mBC). However, in FL metastatic non-squamous NSCLC, OS benefit was less robust in females treated with Bv + chemotherapy (CTx). In order to examine whether there is a gender effect upon efficacy in other trials, an analysis of results from randomized ph II and open-label ph III trials with Bv in mCRC (and a randomized ph II trial in SL NSCLC) was conducted for females. Methods: RR, PFS and OS are summarized for females in the following trials (primary endpoint): 1] ph II FL mCRC (PFS); 2] ph III: FL mCRC (OS); 3] ph III SL mCRC (OS); 4] ph II SL NSCLC (PFS); 5] ph III FL NSCLC (OS). Results: Table 1 presents results of Studies 1 - 5. RR is presented as the difference in RR between Bv and respective control arms. Conclusions: Clinical benefit with Bv + CTx compared to CTx-alone was observed in OS for females in studies which included Bv in treatment of mCRC. OS observed in females in Study 5 (FL NSCLC) is inconsistent with findings in mCRC, mBC and SL NSCLC, and the improvement for PFS and RR for females in Study 5. As such, there is no compelling evidence to suggest lack of benefit with Bv in females.

[Table: see text] [Table: see text]

Behavioural and psychological symptoms of Alzheimer type dementia are not correlated with plasma homocysteine concentration

BACKGROUND/AIMS

Vitamin B12 and folate deficiencies have been associated with cognitive impairment and various psychiatric symptoms but not specifically with behavioural and psychological symptoms of dementia (BPSD). A limitation of previous studies in dementia was lack of concurrent homocysteine measurement especially as it may provide a better indicator of tissue activities of these vitamins. This study was designed to clarify whether a relationship exists between plasma homocysteine concentration and BPSD.

METHODS

Plasma homocysteine, serum vitamin B12 and folate were measured in 23 Alzheimer's disease (AD) patients with BPSD and 27 AD patients without BPSD as determined through the use of the Neuropsychiatric Inventory (NPI). Blood levels of measured substances were also correlated with individual NPI scores and with cumulative NPI scores for different cluster of symptoms.

RESULTS

There was no significant difference (p = 0.956) in the mean plasma homocysteine levels between AD patients with BPSD (17.48 micromol/l) and AD patients without BPSD (17.34 micromol/l). Similarly, there was no significant difference between the two groups in the mean serum B12 (382.61 and 391.60 pg/ml, respectively) and folate (7.95 and 10.02 ng/ml, respectively). Mean levels for both vitamins were well within the laboratory reference range. Neither individual nor cluster NPI scores correlated significantly with plasma homocysteine.

CONCLUSION

This study shows for the first time that BPSD are not associated with hyperhomocysteinaemia in Alzheimer dementia. Although previous studies have identified homocysteine as an independent risk factor in AD, the results reported here do not lend weight to an aetiological role for homocysteine specifically in BPSD.

Differential sensitivity of flounder (Platichthys flesus) in response to oestrogenic chemical exposure: an issue for design and interpretation of monitoring and research programmes

This study was conducted as an initial investigation of 'differential response' in one of the main sentinel organisms used for monitoring programmes in United Kingdom estuaries, the flounder Platichthys flesus. It has been hypothesised that monitoring using species with a wide geographical spread and limited migration, such as flounder, might result in the comparison of different genetic stocks and certainly of populations with differing early life stage contaminant exposure histories. Furthermore, it is probable that these pre-exposure and genetic differences could manifest themselves in an ability to respond differently to contaminant exposure, so-called 'differential response'. It is important that the extent and nature of this response is understood, if we want to be able to fully interpret the monitoring data from such programmes. During this study, flounder were collected from four separate sources; wild caught fish from the estuaries of the Rivers Alde, Mersey and Tyne, and farmed flounder from Port Erin Farm, Isle of Man. Under controlled laboratory conditions, groups of fish from each source were exposed to water-borne concentrations of the synthetic oestrogen ethynylestradiol (EE2) at a nominal concentration of 50 ng/l. Plasma was taken from each male fish after 6 and 10 days exposure and analysed for the presence of vitellogenin (VTG) using an ELISA technique. Significant levels of VTG induction were evident in fish from all sources after both 6 and 10 days exposure. Flounder from the Mersey were the only fish with significantly elevated initial background levels of VTG (day 0) and this appeared to be reflected in that these specimens showed the highest induction response after day 6. However, after day 10, fish from all other sites had a slightly higher mean VTG than those from the Mersey which showed significantly (p < 0.05) lower mean plasma VTG. It is suggested that other differential responses may have been masked by the use of a high dose of EE2 which produced maximum induction in nearly all fish. The findings of the study are discussed in terms of implications for further research into the differential response issue and how the initial plasma VTG figures contribute to a time-series from the Mersey, Tyne and Alde estuaries.

Development of a holistic admission assessment: an integrated care pathway for the hospice setting

This article describes the development of a holistic admission assessment for all inpatients admitted to a 66-bedded hospice, structured in the form of an integrated care pathway (ICP). The need for an improved assessment process was identified by clinical staff, who recognized that the existing assessment was not truly holistic and was dependent on the skills of the assessors. The assessment also lacked appropriate goals and actions. The recently published National Institute for Clinical Excellence (NICE) guidance on Improving Supportive and Palliative Care for Adults with Cancer, has also highlighted key areas for the improvement of patient assessment in specialist palliative care (NICE, 2004). Implementation of the ICP has resulted in a systematic and timely holistic assessment process for patients. The ICP addresses effectively the NICE recommendations for the assessment of specialist palliative care patients.

Speech and swallowing following radial forearm flap reconstruction of major soft palate defects

Velopharyngeal function is often compromised by the resection and reconstruction of oropharyngeal and palatal tumours. While free tissue transfer has improved the outcomes of head and neck reconstruction. In general, palatal reconstruction remains a challenge. Velopharyngeal function was analysed in eight patients following microsurgical reconstruction of defects of between 50 and 100% of the soft palate. The radial forearm fasciocutaneous free flap was used in all cases. The outcome of reconstruction was analysed by patient questionnaire and with standardised tests of speech and swallowing function. Velopharyngeal function post-operatively ranged from poor to near normal. Poor function appeared due to the loss of active elevation and contracture of the reconstructed palate producing failure of velopharyngeal closure during swallowing and speech. The results emphasise the limitations of reconstruction of a dynamic structure such as the soft palate with the static fold of skin and soft tissue produced by a fasciocutaneous flap. The relatively poor results obtained suggest that an anatomical approach to soft palate reconstruction is inadequate and reduction of the calibre of the velopharyngeal aperture is required to compensate for the lack of mobility in the reconstructed palate.

Paediatric near-drowning: mortality and outcome in a temperate climate

The decision whether to continue to resuscitate the paediatric victim of near-drowning is influenced by potential poor neurological outcome. A low core body temperature at presentation is frequently cited as a reason to continue resuscitation. We report the case of an 11 month old infant admitted to the intensive care unit following near-drowning and a prolonged resuscitation. The infant's core body temperature was 29 degrees C. Cardiac output was restored, but the child remains in a persistent vegetative state. We present the results of a ten year review of near-drowning in a tertiary referral institution, to evaluate the mortality and outcome in a temperate climate. Thirteen patients were identified in the review. The mortality was 23%. The incidence of a persistent vegetative state was 15%. Asystole, immersion time greater than 15 minutes, resuscitation time longer than 30 minutes, the administration of epinephrine, and a low core body temperature were associated with a poor outcome.

Influence of operating conditions and vessel size on oxygen transfer during cellulase production

The production of low-cost cellulase enzyme is a key step in the development of an enzymatic-based process for conversion of lignocellulosic biomass to ethanol. Although abundant information is available on cellulase production, little of this work has examined oxygen transfer. We investigated oxygen transfer during the growth of Trichoderma reesei, a cellulase-producing microorganism, on soluble and insoluble substrates in vessel sizes from 7 to 9000 L. Oxygen uptake rates and volumetric mass transfer coefficients (kLa) were determined using mass spectroscopy to measure off gas composition. Experimentally measured kLa values were found to compare favorably with a kLa correlation available in the literature for a non-Newtonian fermentation broth during the period of heavy cell growth.

Quality of life in advanced non-small-cell lung cancer: results of a Southwest Oncology Group randomized trial

PURPOSE

The main purpose of this paper is to present the results of a randomized trial comparing the effects of two chemotherapy regimens on the Quality of life (QOL) of patients with advanced non-small-cell lung cancer (NSCLC). Trials in advanced stage disease represent an important treatment context for QOL assessment. A second purpose of this paper is to examine methods for handling the level of missing data commonly observed in the advanced stage disease context.

METHODS

Patients were randomized to receive cisplatin plus vinorelbine or carboplatin plus paclitaxel. The QOL of 222 patients was assessed with the Functional Assessment of Cancer Therapy-Lung (FACT-L) prior to randomization; follow-up assessments occurred at 13 and 25 weeks. Three methods were used to analyze the QOL data: (1) cross-sectional analysis of four patient categories (improved, stable, missing, and declined) based on changes in the FACT-L score, (2) a mixed linear model, and (3) a pattern mixture model. The longitudinal analyses addressed two potential data biases.

RESULTS

Questionnaire submission rates were 91% at baseline, 68% at 13 weeks, and 47% at 25 weeks. The cross-sectional and mixed linear model analyses did not show significant differences by treatment arm in patient-reported QOL. The pattern mixture model analysis, more appropriate given non-ignorable missing data, also found no statistically significant effect of treatment on patient QOL.

CONCLUSION

We present a sensitivity analysis approach with multiple methods for analyzing treatment effects on patient QOL in the presence of substantial, non-ignorable missing data in an advanced stage disease clinical trial. We conclude that the two treatment arms did not differ statistically in their effects on patient QOL over a 25-week treatment period.

Anaesthesia for children with epidermolysis bullosa: a review of 20 years' experience

BACKGROUND AND OBJECTIVE

Epidermolysis bullosa is a rare, genetically determined disorder characterized by excessive susceptibility of the skin and mucosa to separate from the underlying tissues after mechanical trauma. Patients suffering from this disease may have multiple medical problems, but the risk of anaesthesia is attributed mainly to oropharyngeal involvement; airway management may be hazardous and preservation of mucosa and skin integrity problematical. There is a paucity of data in the literature concerning the perioperative management of children with epidermolysis bullosa. We present our experience of managing 54 general anaesthetics (and two local anaesthetics) over the past 20 years.

METHODS

The case notes of 16 children with epidermolysis bullosa were reviewed. The children underwent surgical procedures under local or general anaesthesia over a 20-year period.

RESULTS

Fifty-four general and two local anaesthetics were administered for 58 procedures in 10 children (mean age 12.6 years). Surgical procedures included oesophageal dilatation (24), insertion/revision of gastrostomy (16), dental procedures (10), hand surgery (2), skin biopsy (2) and others (4). Anaesthesia was induced by inhalation in 73.4% of patients and the airway was maintained with an endotracheal tube in 64.8%. Monitoring of anaesthesia was performed with pulse oximetry (89%), whereas electrocardiography and non-invasive blood pressure monitoring were used in 16.6% of cases each. The mean duration of anaesthesia was 64 min. Tracheal intubation was difficult in two of the five children who were intubated. Mucocutaneous blistering occurred in three children, otherwise there was no attributable morbidity.

CONCLUSION

With maximal skin and mucous membrane protection, anaesthesia in children with epidermolysis bullosa may be undertaken with few sequelae.

Health insurance expansion through states in a pluralistic system

The United States continues to stand almost alone among developed nations in its lack of universal health care coverage. In this essay, we argue that even though the debate over whether the federal government or states should lead the effort to expand health care coverage under the federal system is relevant in strategizing how to cover the uninsured; the more critical issues stem from the challenge of the mixed and fragmented mode of public-private financing of our pluralistic health care system. We base this argument on (1) an in-depth review of Oregon's and Tennessee's five years of experience with broad coverage reform in the context of the United States health care system and on (2) a more abbreviated review of other state experiences in providing health care coverage. We conclude from our review that when the will exists, states can substantially expand coverage. However, as one moves up the income scale, political support and resources are harder to come by. Further, concerns grow about the interface of public and private coverage, with issues of "crowd out" and other distributional questions dominating the discussion of coverage expansion as policy makers focus less on how to cover people than on how to make sure one kind of coverage doesn't preempt another. Concern for crowd out can then lead to policies that keep out some of the very people policy makers may want to cover. In this context the question whether states or the federal government is more likely to succeed in expanding coverage is eclipsed by the more fundamental challenges raised by pluralism. Neither federal nor state government is likely to be fully successful without first identifying ways of better coordinating public and private activities and resources to provide continuous and affordable coverage.

The safety and effectiveness of the Le Fort I approach to removing central skull base lesions

The difficulty of gaining access to the central skull base has led to the development of many surgical approaches to this area during the past decade. Yet we believe that the Le Fort I technique, which has been used for almost 140 years in orthognathic surgery, is still an excellent approach to treating anterior skull base lesions. This procedure, which entails the horizontal sectioning of the dentoalveolar maxillary segment, seemed to fall out of favor with otolaryngologists after a few reports of complications surfaced during the past 10 to 15 years. In this article, we report a series of seven patients whom we treated with a Le Fort I approach during a 3-year period for a variety of benign and malignant anterior skull base lesions. We have encountered no significant complications of surgery or recurrence of disease at a maximum postoperative followup of 3 years.

Vaccination coverage and physician distribution in the United States, 1997

BACKGROUND

How many physicians are needed in the United States and how they should be allocated geographically and among specialties has been the subject of intense debate, a debate that has often focused more on costs to third-party payers and government than on benefits to health. Child health is a central aspect of public health, and immunization is one of its most cost-effective and easily measured interventions.

OBJECTIVE

To examine the association of immunization rates and delivery characteristics with the distribution of child health physicians in the United States in 1997.

DESIGN

Cross-sectional ecological study, using the state as the unit of analysis, immunization rates and delivery characteristics (from the National Immunization Survey) as the main outcome measures, concentration of the principal physician specialties providing routine care to children (pediatric, family, and general physicians from the American Medical Association Masterfile) as the main risk factor, while controlling for demographic and economic factors (from the Bureau of the Census and other sources).

RESULTS

Of the 96 689 physicians providing routine care to children, 37% were pediatric, 49% family, and 14% general physicians. Higher rates of vaccination, private sector vaccination, and increased numbers of public and private vaccination sites were all associated with the concentration of pediatricians but not of family or general physicians. The distribution of pediatricians was strongly associated with the distribution of residency positions.

CONCLUSIONS

Pediatrician distribution is a strong correlate to immunization rates and delivery characteristics. Opportunities to affect pediatrician distribution may exist with allocation of residency positions.

Oil and water? Lessons from Maryland's effort to protect safety net providers in moving to Medicaid managed care

Studies have highlighted the tensions that can arise between Medicaid managed care organizations and safety net providers. This article seeks to identify what other states can learn from Maryland's effort to include protections for safety net providers in its Medicaid managed care program--HealthChoice. Under HealthChoice, traditional provider systems can sponsor managed care organizations, historical providers are assured of having a role, patients can self-refer and have open access to certain public health providers, and capitation rates are risk adjusted through the use of adjusted clinical groups and claims data. The article is based on a week-long site visit to Maryland in fall 1998 that was one part of a seven-state study. Maryland's experience suggests that states have much to gain in the way of "good" public policy by considering the impact of their Medicaid managed care programs on the safety net, but states should not underestimate the challenges involved in balancing the need to protect the safety net with the need to contain costs and minimize the administrative burden on providers. No amount of protection can compensate for a poorly designed or implemented program. As the health care environment continues to change, so may the need for and the types of protections change. It also may be most difficult to guarantee adequate protections to those who need it most--among relatively financially insecure providers that have a limited management infrastructure and that depend heavily on Medicaid and the state for funds to care for the uninsured.

The status of immunization measurement and feedback in the United States

BACKGROUND

A large body of scientific and programmatic data has demonstrated that provider measurement and feedback raises immunization coverage. Starting in 1995, Congress required that all states measure childhood immunization coverage in all public clinics, and federal grant guidelines encourage private practice measurements.

OBJECTIVES

To determine state immunization measurement rates and examine risk factors for high rates.

METHODS

Review of 1997 state reports, with correlation of measurement rates to birth cohort and provider numbers, public/private proportions, and vaccine distribution systems.

RESULTS

Of the 9505 public clinics, 48% were measured; 4 states measured all clinics; 29 measured a majority. Measurement rates were highest for Health Department clinics (67%), lower for community/migrant health centers (39%), and lowest for other clinics (22%). Rates were highly correlated among categories of clinics (r>+0.308, P<.03), and the fewer the clinics, the higher the measurement rates (r = -0.351, P =. 01), but other factors were not significant. Of the 41,378 private practices, 6% were measured; no state measured all its practices; 1 measured a majority. Private practice measurement rates were not correlated to public clinic measurement rates or other factors examined. Of the 50,883 total providers, 14% were measured; no state measured all providers; 2 measured a majority. A trend toward higher measurement rates was found in states with fewer providers (r = -0. 266, P =.06).

CONCLUSIONS

Three years after the congressional mandate, only a minority of public clinics and very few private practices had their immunization coverage measured. Greater efforts will be needed to assure implementation of the intervention. Arch Pediatr Adolesc Med. 2000;154:832-836

NOD/LtSz-Rag1null mice: an immunodeficient and radioresistant model for engraftment of human hematolymphoid cells, HIV infection, and adoptive transfer of NOD mouse diabetogenic T cells

Development of a small animal model for the in vivo study of human immunity and infectious disease remains an important goal, particularly for investigations of HIV vaccine development. NOD/Lt mice homozygous for the severe combined immunodeficiency (Prkdcscid) mutation readily support engraftment with high levels of human hematolymphoid cells. However, NOD/LtSz-scid mice are highly radiosensitive, have short life spans, and a small number develop functional lymphocytes with age. To overcome these limitations, we have backcrossed the null allele of the recombination-activating gene (Rag1) for 10 generations onto the NOD/LtSz strain background. Mice deficient in RAG1 activity are unable to initiate V(D)J recombination in Ig and TCR genes and lack functional T and B lymphocytes. NOD/LtSz-Rag1null mice have an increased mean life span compared with NOD/LtSz-scid mice due to a later onset of lymphoma development, are radioresistant, and lack serum Ig throughout life. NOD/LtSz-Rag1null mice were devoid of mature T or B cells. Cytotoxic assays demonstrated low NK cell activity. NOD/LtSz-Rag1null mice supported high levels of engraftment with human lymphoid cells and human hemopoietic stem cells. The engrafted human T cells were readily infected with HIV. Finally, NOD/LtSz-Rag1null recipients of adoptively transferred spleen cells from diabetic NOD/Lt+/+ mice rapidly developed diabetes. These data demonstrate the advantages of NOD/LtSz-Rag1null mice as a radiation and lymphoma-resistant model for long-term analyses of engrafted human hematolymphoid cells or diabetogenic NOD lymphoid cells.

Substituting proxy ratings for patient ratings in cancer clinical trials: an analysis based on a Southwest Oncology Group trial in patients with brain metastases

In studies of the effect of cancer treatment in the advanced disease setting, researchers have attempted to avoid missing data for quality of life (QOL) assessments by either substituting proxy for patient assessments from the outset or by interspersing proxy measures when patients are unable to respond. Although poor agreement between patient and proxy assessments has been amply demonstrated in the literature, interest in using proxy measures persists. Completion of the Spitzer QL-Index by a small sample of patients with brain metastases and family member proxies provided data for evaluating the ability to substitute proxy for patient QOL assessments. These data cannot address treatment efficacy due to the modest sample size. Rather, the analyses serve to alert researchers to the important distinction (in a clinical trial setting) between agreement and the use of the proxy as a surrogate. We present several methods for evaluating the accuracy of proxy measures and for identifying other sources of error and bias that may vary with time or with treatment arm. Lin's concordance correlation coefficient suggests that proxies are generally a poor substitute for capturing a patient's perspective of his/her QOL. A longitudinal analysis suggests that the use of proxy rather than patient responses could lead to different conclusions concerning radiation therapy's effect on QOL.

Radiation with concurrent late chemotherapy intensification ('chemoboost') for locally advanced head and neck cancer

The aim of this study was to review our experience with a treatment regimen that combined conventionally fractionated radiation therapy (70 Gy over 7 weeks) with chemotherapy (cisplatin and fluorouracil), given concurrently in the last 2 weeks of radiation therapy in patients with previously untreated advanced squamous cell cancer of the head and neck region.Twenty-eight patients, all but two having UICC stage IV disease, were treated at the Peter MacCallum Cancer Institute between November 1995 and April 1998. Planned chemotherapy consisted initially of continuous infusion at 10 mg/m(2) per day of cisplatin and 400 mg/m(2) per day of fluorouracil on days 1-5 of weeks 6 and 7 of a conventionally fractionated course of radiotherapy. After the first 14 patients, the dose of fluorouracil was reduced to 360 mg/m(2) per day because of acute toxicity.36.8 months), with an estimated 50% surviving at 2 years (CI, 29-71%). Sixteen patients (57%) developed confluent mucositis and 11 (39%) developed patchy mucositis. The median duration of mucositis for these 27 patients was 1.5 months. Seventeen patients (61%) required nutritional support for a median duration of 1.4 months. Fourteen patients (50%) had grade three skin reactions, and 12 (43%) had one or more other significant (Grade 3) toxicities, predominantly infective. Grade 3 late toxicity has been observed in three patients to date (three xerostomia, including one with severe depression), and one patient had chronic ulceration of the oral tongue (grade 4). This chemoradiation regimen achieved an excellent complete response rate and good locoregional control at 2 years in patients with a poor initial prognosis. Acute toxicity was significant but manageable. The regimen offers an alternative to surgery and postoperative radiation therapy in locally advanced head and neck cancer.

Ceramide increases steroid hormone production in MA-10 Leydig cells

Ceramide is known to have major roles in the control of cell proliferation, differentiation, and apoptosis. Recent studies also have shown that ceramide affects steroid production by JEG-3 choriocarcinoma cells, acutely dispersed rat Leydig cells, and ovarian granulosa cells, but the mechanism by which this occurs is unknown. Because ceramide induces apoptosis in many different cell types, we hypothesized that ceramide might affect steroidogenesis and/or induce apoptosis in MA-10 murine Leydig cells. To test this, MA-10 cells were incubated with either the water soluble C2-ceramide, (N-acetyl-sphingosine, 0.01-10 cm); bacterial sphingomyelinase (1-100 mU/ml); or C2-dihydroceramide (N-acetyl-sphinganine, 0.1-10 microM). The data show that N-acetyl-sphingosine significantly increased basal (0.87 +/- 0.2 vs. 0.42 +/- 0.09 ng/mg cell protein, P < 0.01) and human chorionic gonadotropin (hCG) stimulated progesterone (P) synthesis (204 +/- 12 vs. 120 +/- 5 ng/mg cell protein, P < 0.001); as did sphingomyelinase (basal P = 0.83 +/- 0.1 ng/mg cell protein, P < 0.01; hCG stimulated P = 173 +/- 7 ng/mg cell protein, P < 0.001). C2-dihydroceramide also increased basal P synthesis but was less effective than ceramide on a molar basis. Neither sphingomyelinase (100 mU/ml) nor ceramide (10 microM) had any effect on cAMP production or human chorionic gonadotropin binding; and neither induced any signs of apoptosis (FragEL DNA fragmentation assay and electron microscopy). Cells incubated with anti-Fas (300 ng/ml) demonstrated DNA fragmentation, nuclear condensation, and frequent apoptotic bodies, but had no change in P synthesis. These data show that ceramide significantly increases MA-10 Leydig cell P synthesis but does not induce apoptosis. The mechanism by which ceramide increases steroid hormone synthesis remains unknown but does not appear to be linked to the induction of apoptosis in MA-10 cells.

Immunization performance measurement in a changing immunization environment

OBJECTIVE

The measurement of performance in the delivery of recommended vaccinations for children is used frequently as a marker for quality of care and as an outcome for studies of interventions to improve immunization coverage levels. The critical element of immunization performance measurement is the determination of immunization status. This methodologic review 1) discusses immunization status as a measure of quality of primary care for children, 2) describes immunization status measures used in immunization intervention studies, and 3) examines selected technical issues of immunization status measurement.

METHODS AND TOPICS

1) Description of the characteristics of immunization status measurements obtained by a systematic review of studies published between 1980 and 1997 on interventions to raise immunization coverage, and 2) illustration of technical considerations for immunization status measurement using one local database and one national database of immunization histories. Technical issues for immunization status measurement include 1) the need to use documented immunization histories rather than parental recall to determine immunization status, 2) the need to link records across providers to obtain complete records, 3) the sensitivity of immunization status to missing immunization data, and 4) the potential of measures incorporating combinations of immunizations to underestimate the degree of vaccination in a population.

CONCLUSIONS

Immunization performance measurement has many characteristics of a robust quality of care measure, including high acceptance by primary care providers of routine vaccination, association of immunization status with the conduct of other clinical preventive services, agreed-on technical and programmatic standards of care, and legislative requirements for medical record documentation. However, it is not without challenges. Careful attention to technical issues has potential to improve immunization delivery health services research.

ENT malignancies. What the GP needs to know

BACKGROUND

The head and neck are sites that are accessible to examination, therefore early detection of cancers in these sites should be simple.

OBJECTIVE

This article discusses the commoner malignant tumours encountered in the various head and neck subsites. It gives an overview of the types of tumours that occur and the presenting features which allow us to distinguish them from benign disorders and facilitate much earlier diagnosis. Recent advances in diagnostic imaging and treatment are discussed.

DISCUSSION

Improved outcomes for patients with head and neck cancers will occur with earlier detection and community education about risk factors.

Impact of a large-scale immunization initiative in the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC)

CONTEXT

Inner-city immunization rates have lagged behind those in other areas of the country.

OBJECTIVE

To evaluate the impact of an initiative linking immunization with distribution of food vouchers in the inner city.

DESIGN

Retrospective analysis of immunization data gathered in 1996 and 1997.

SETTING

Nineteen Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) sites serving 30% of the Chicago, III, birth cohort.

PARTICIPANTS

A total of 16581 children 24 months old or younger.

INTERVENTIONS

Voucher incentives (varying frequency of food voucher issuance based on immunization status) and assessment of immunization status and referral to immunization provider.

MAIN OUTCOME MEASURES

Age-appropriate immunization rates and WIC enrollment rates.

RESULTS

During the 15-month period of evaluation, immunization rates increased from 56% to 89% at sites performing voucher incentives. The proportion of children needing voucher incentives declined from 51% to 12%. Sites performing assessment and referral, but not providing voucher incentives, showed no evidence of improvement in immunization coverage. No difference was observed in enrollment rates between sites performing voucher incentives and those that did not.

CONCLUSION

Applied in a large-scale, programmatic fashion, voucher incentives in WIC can rapidly increase and sustain high childhood immunization rates in an inner-city population.

Managed care and low-income populations: recent state experiences

This DataWatch examines the relationship between managed care enrollment and access to care for low-income adults with Medicaid and compares their experience with that of low-income, privately insured managed care enrollees. Medicaid managed care enrollees are more likely than low-income, privately insured managed care enrollees to be poorer, have health problems, and experience access problems. Compared with low-income populations in fee-for-service care, managed care enrollees, whether in Medicaid or privately insured, are not appreciably different in having a usual source of care, having a regular provider, or emergency room use but report more problems in obtaining care and are more likely to be dissatisfied with their health plans.

Use of protein-C concentrate, heparin, and haemodiafiltration in meningococcus-induced purpura fulminans

BACKGROUND

Inflammatory and coagulation processes are both affected in meningococcaemia. Severe acquired protein-C deficiency in meningococcaemia is usually associated with substantial mortality: in survivors, skin grafts, amputation, and end-organ failure are not uncommon. Protein C is a natural anticoagulant and also has important anti-inflammatory activity. We assessed the effects of early replacement therapy with protein-C concentrate together with continuous veno-venous haemodiafiltration and conventional treatment in meningococcaemia.

METHODS

12 patients aged between 3 months and 27 years with meningococcaemia and severe acquired protein-C deficiency (mean 0.20 IU/mL) were studied. All patients had septic shock, widespread purpura, skin necrosis, and disseminated intravascular coagulopathy. After a test dose of protein-C concentrate, patients received a continuous infusion with the dose adjusted daily to keep the plasma concentration between 0.8 and 1.2 IU/mL. 11 patients were given unfractionated intravenous heparin (10-15 IU kg-1 h-1). Nine patients had haemodiafiltration and one had peritoneal dialysis. The Glasgow meningococcal septicaemia prognostic score and the paediatric risk of mortality score predicted a minimum mortality of 80% and 57%, respectively.

FINDINGS

No patient died. No adverse reactions to the treatment were seen. Two patients had lower-limb amputations, one of whom had a thrombotic cerebrovascular accident; both patients had received the protein-C concentrate and heparin later than the rest of the group (60 h [16.97] vs 12 h [3.13]). One patient developed chronic renal failure despite receiving protein-C infusion 15 h after admission.

INTERPRETATION

The acquired severe deficiency of protein C in meningococcaemia contributes to the pathogenesis of the thrombotic necrotic lesions in the skin and other organs and probably has an important role in the inflammatory response. Protein-C therapy is merely one approach to improve the host response in this syndrome. We suggest that a double-blind, randomised, controlled multicentre trial is needed to confirm our results.

Insurance matters for low-income adults: results from a five-state survey

Using survey data from 2,000 low-income adult respondents in each of five states, this DataWatch assesses how uninsured, low-income adults differ from low-income adults who have public or private insurance and how Medicaid expansions have affected insurance coverage patterns across states with different eligibility policies. Findings show that the proportion of low-income uninsured adults is two to three times higher in states that have not expanded Medicaid eligibility beyond relatively low welfare levels. Compared with persons who have either Medicaid or private insurance, uninsured persons report more difficulties getting needed care, are less likely to have a regular provider, and rate the care they do receive as lower quality.

Unmet long-term care needs of elderly people in the community: a review of the literature

The extent of unmet need, or the extent to which needed assistance is unavailable for insufficient, is an important issue in public policy and financing of health and support services. This article reviews the research of literature to assess how unmet method is measured, and the extent of unmet needs among elderly people in the community. Measurement difficulties include variable definitions and measures of need across studies, the relative dearth of studies which undertake to measure unmet needs, and varying methodologies used to estimate need and unmet need. In addition, some measures of status and need, such as cognitive impairment and care giver burden are excluded from many estimates. Estimates of unmet need range from around 2 percent to about 35 percent of community dwelling elders, depending on what is included or excluded from the definition. Unmet need is associated with higher disability levels and living alone. The literature suggests that estimates of future unmet need will be mitigated by declining disability levels and increased use of assistive devices among the elder population.

Postanaesthetic shivering in children

This study was designed to assess the incidence, severity and possible aetiological factors of postanaesthetic shivering in children. Three hundred and seventy-six children undergoing general anaesthesia were enrolled in the study. Tympanic membrane temperatures were recorded pre-operatively and every 15 min postoperatively in the recovery room until discharge to the ward. Also recorded were all anaesthetic data including fluid administration, methods of temperature preservation used, sedation scores and shivering (using a four-point scale). The overall incidence of shivering was 14.4%. Multiple regression analysis identified three factors that were significantly related to shivering: age, the administration of atropine and peri-operative temperature changes. Children who shivered rewarmed faster in the recovery room.

The effect of passive smoking on the incidence of airway complications in children undergoing general anaesthesia

The aim of this study was to assess whether passive smoking affected the frequency of airway complications in children undergoing general anaesthesia. One hundred and twenty-five children undergoing general anaesthesia for elective daycase surgery were monitored for adverse respiratory events and desaturation during induction, intra-operatively and in the recovery room. Oxygen saturation was monitored throughout and a venous sample was taken for estimation of carboxyhaemoglobin levels. Parents were asked to fill in a questionnaire detailing their smoking habits. Sixty-three of the children were passive smokers with a potential daily exposure varying from 5-130 cigarettes. There was no difference in the frequency of respiratory events between passive smokers and those not exposed to cigarette smoke at induction or intra-operatively. However, in the recovery room, desaturation was significantly more common in passive smokers (p < 0.02). This was related to the cumulative number of cigarettes smoked by individuals to whom the child was exposed (p < 0.05). Neither carboxyhaemoglobin levels nor domiciliary address were predictive of desaturation. This study suggests that passive smoking contributes to postoperative arterial oxygen desaturation following general anaesthesia in children.

Modification of pain on injection of propofol. A comparison of pethidine and lignocaine

One hundred and fifty ASA 1 and 2 patients were randomly allocated to receive pethidine 25 mg (1 ml), lignocaine 10 mg (1 ml) or 0.9% saline (1 ml) on a double-blind basis, as pretreatment to reduce pain on injection of propofol. Both active treatments were significantly better than placebo at preventing pain (p < 0.01). Lignocaine was most effective in preventing pain in men (p < 0.05) whilst pethidine was more effective in women (p < 0.05).

Pain relief with low-dose intravenous clonidine in a child with severe burns

The case of an 11-year-old boy who suffered second and third degree burns to 78% of his body is reported. The large doses of morphine used as analgesia resulted in severe side effects: ventilatory dependence, impairment of gastrointestinal function and psychological disturbance. Intravenous lignocaine was added without benefit. The addition of low-dose intravenous clonidine, however, precipitated a dramatic reduction in morphine consumption with an attendant improvement in ventilatory, gastrointestinal and psychological functions.