South African healthcare reforms towards universal healthcare - where to next?

The National Assembly approval of the National Health Insurance (NHI) Bill represents an important milestone, but there are many uncertainties concerning its implementation and timeline. The challenges faced by the South African healthcare system are huge, and we cannot afford to wait for NHI to address them all. It is critical that the process of strengthening the health system to advance universal healthcare (UHC) begins now, and there are several viable initiatives that can be implemented without delay. This article examines potential scenarios after the Bill is passed and ways in which UHC could be advanced. It begins with an overview of the trajectory of health system reform since 1994, then examines the scenarios that may emerge once the Bill is passed by Parliament and makes a case for finding ways in which UHC could be advanced within the country, regardless of any legal or financial barriers that may delay or limit NHI implementation.

Defining trajectories of response in patients with psoriasis treated with biologic therapies

BACKGROUND

The effectiveness and cost-effectiveness of biologic therapies for psoriasis are significantly compromised by variable treatment responses. Thus, more precise management of psoriasis is needed.

OBJECTIVES

To identify subgroups of patients with psoriasis treated with biologic therapies, based on changes in their disease activity over time, that may better inform patient management.

METHODS

We applied latent class mixed modelling to identify trajectory-based patient subgroups from longitudinal, routine clinical data on disease severity, as measured by the Psoriasis Area and Severity Index (PASI), from 3546 patients in the British Association of Dermatologists Biologics and Immunomodulators Register, as well as in an independent cohort of 2889 patients pooled across four clinical trials.

RESULTS

We discovered four discrete classes of global response trajectories, each characterized in terms of time to response, size of effect and relapse. Each class was associated with differing clinical characteristics, e.g. body mass index, baseline PASI and prevalence of different manifestations. The results were verified in a second cohort of clinical trial participants, where similar trajectories following the initiation of biologic therapy were identified. Further, we found differential associations of the genetic marker HLA-C*06:02 between our registry-identified trajectories.

CONCLUSIONS

These subgroups, defined by change in disease over time, may be indicative of distinct endotypes driven by different biological mechanisms and may help inform the management of patients with psoriasis. Future work will aim to further delineate these mechanisms by extensively characterizing the subgroups with additional molecular and pharmacological data.

Cost-effectiveness of intensive care for hospitalized COVID-19 patients: experience from South Africa

BACKGROUND

Given projected shortages of critical care capacity in public hospitals during the COVID-19 pandemic, the South African government embarked on an initiative to purchase this capacity from private hospitals. In order to inform purchasing decisions, we assessed the cost-effectiveness of intensive care management for admitted COVID-19 patients across the public and private health systems in South Africa.

METHODS

Using a modelling framework and health system perspective, costs and health outcomes of inpatient management of severe and critical COVID-19 patients in (1) general ward and intensive care (GW + ICU) versus (2) general ward only (GW) were assessed. Disability adjusted life years (DALYs) were evaluated and the cost per admission in public and private sectors was determined. The model made use of four variables: mortality rates, utilisation of inpatient days for each management approach, disability weights associated with severity of disease, and the unit cost per general ward day and per ICU day in public and private hospitals. Unit costs were multiplied by utilisation estimates to determine the cost per admission. DALYs were calculated as the sum of years of life lost (YLL) and years lived with disability (YLD). An incremental cost-effectiveness ratio (ICER) - representing difference in costs and health outcomes of the two management strategies - was compared to a cost-effectiveness threshold to determine the value for money of expansion in ICU services during COVID-19 surges.

RESULTS

A cost per admission of ZAR 75,127 was estimated for inpatient management of severe and critical COVID-19 patients in GW as opposed to ZAR 103,030 in GW + ICU. DALYs were 1.48 and 1.10 in GW versus GW + ICU, respectively. The ratio of difference in costs and health outcomes between the two management strategies produced an ICER of ZAR 73,091 per DALY averted, a value above the cost-effectiveness threshold of ZAR 38,465.

CONCLUSIONS

Results indicated that purchasing ICU capacity from the private sector during COVID-19 surges may not be a cost-effective investment. The 'real time', rapid, pragmatic, and transparent nature of this analysis demonstrates an approach for evidence generation for decision making relating to the COVID-19 pandemic response and South Africa's wider priority setting agenda.

The Secure Anonymised Information Linkage databank Dementia e-cohort (SAIL-DeC)

Introduction

The rising burden of dementia is a global concern, and there is a need to study its causes, natural history and outcomes. The Secure Anonymised Information Linkage (SAIL) Databank contains anonymised, routinely-collected healthcare data for the population of Wales, UK. It has potential to be a valuable resource for dementia research owing to its size, long follow-up time and prospective collection of data during clinical care.

Objectives

We aimed to apply reproducible methods to create the SAIL dementia e-cohort (SAIL-DeC). We created SAIL-DeC with a view to maximising its utility for a broad range of research questions whilst minimising duplication of effort for researchers.

Methods

SAIL contains individual-level, linked primary care, hospital admission, mortality and demographic data. Data are currently available until 2018 and future updates will extend participant follow-up time. We included participants who were born between 1st January 1900 and 1st January 1958 and for whom primary care data were available. We applied algorithms consisting of International Classification of Diseases (versions 9 and 10) and Read (version 2) codes to identify participants with and without all-cause dementia and dementia subtypes. We also created derived variables for comorbidities and risk factors.

Results

From 4.4 million unique participants in SAIL, 1.2 million met the cohort inclusion criteria, resulting in 18.8 million person-years of follow-up. Of these, 129,650 (10%) developed all-cause dementia, with 77,978 (60%) having dementia subtype codes. Alzheimer's disease was the most common subtype diagnosis (62%). Among the dementia cases, the median duration of observation time was 14 years.

Conclusion

We have created a generalisable, national dementia e-cohort, aimed at facilitating epidemiological dementia research.

Do dental undergraduates think that Thiel-embalmed cadavers are a more realistic model for teaching exodontia?

INTRODUCTION

Teaching exodontia to novice undergraduates requires a realistic model. Thiel-embalmed cadavers retain the flexibility of the soft tissues and could be used to teach exodontia.

OBJECTIVE

The objective was to determine whether Thiel-embalmed cadavers were perceived to be a more realistic model by undergraduates in comparison with mannequins.

MATERIALS AND METHODS

Over a period of 4 years (2011-2014), students were randomly assigned into two groups: those taught exodontia on mannequins only (NT) and those who also experienced cadaveric teaching (T). This was followed by an assessment.

RESULTS

There were 174 students in the T group and 108 in the NT group. Sixty-five per cent of the T group and 69% of the NT group provided feedback. Ninety-eight per cent (98%) felt that they had been advantaged by being included in the group compared with 95% in the NT who felt disadvantaged. The majority (98%) thought that using the cadavers was advantageous and gave a realistic feel for soft tissue management (89%) and that it was similar to managing a patient (81%). Self-reported confidence in undertaking an extraction was not different between the two groups (P=.078), and performance in the extraction assessment was not significantly different between the two groups over the 4 years (P=.8).

CONCLUSION

The Thiel-embalmed cadavers were well received by the students who found it a more realistic model for exodontia than a mannequin, even though this did not impact on their performance in a following assessment. Future work on these cadavers may be expanded to include surgical procedures.

Structural Characterisation Reveals Mechanism of IL-13-Neutralising Monoclonal Antibody Tralokinumab as Inhibition of Binding to IL-13Rα1 and IL-13Rα2

Interleukin (IL)-13 is a pleiotropic T helper type 2 cytokine frequently associated with asthma and atopic dermatitis. IL-13-mediated signalling is initiated by binding to IL-13Rα1, which then recruits IL-4Rα to form a heterodimeric receptor complex. IL-13 also binds to IL-13Rα2, considered as either a decoy or a key mediator of fibrosis. IL-13-neutralising antibodies act by preventing IL-13 binding to IL-13Rα1, IL-4Rα and/or IL-13Rα2. Tralokinumab (CAT-354) is an IL-13-neutralising human IgG4 monoclonal antibody that has shown clinical benefit in patients with asthma. To decipher how tralokinumab inhibits the effects of IL-13, we determined the structure of tralokinumab Fab in complex with human IL-13 to 2 Å resolution. The structure analysis reveals that tralokinumab prevents IL-13 from binding to both IL-13Rα1 and IL-13Rα2. This is supported by biochemical ligand-receptor interaction assay data. The tralokinumab epitope is mainly composed of residues in helices D and A of IL-13. It is mostly light chain complementarity-determining regions that are driving paratope interactions; the variable light complementarity-determining region 2 plays a key role by providing residue contacts for a network of hydrogen bonds and a salt bridge in the core of binding. The key residues within the paratope contributing to binding were identified as Asp50, Asp51, Ser30 and Lys31. This study demonstrates that tralokinumab prevents the IL-13 pharmacodynamic effect by binding to IL-13 helices A and D, thus preventing IL-13 from interacting with IL-13Rα1 and IL-13Rα2.

Protein engineering and preclinical development of a GM-CSF receptor antibody for the treatment of rheumatoid arthritis

BACKGROUND AND PURPOSE

For antibody therapies against receptor targets, in vivo outcomes can be difficult to predict because of target-mediated clearance or antigen 'sink' effects. The purpose of this work was to engineer an antibody to the GM-CSF receptor α (GM-CSFRα) with pharmacological properties optimized for chronic, s.c. treatment of rheumatoid arthritis (RA) patients.

EXPERIMENTAL APPROACH

We used an in silico model of receptor occupancy to guide the target affinity and a combinatorial phage display approach for affinity maturation. Mechanism of action and internalization assays were performed on the optimized antibody in vitro before refining the modelling predictions of the eventual dosing in man. Finally, in vivo pharmacology studies in cynomolgus monkeys were carried out to inform the predictions and support future clinical development.

KEY RESULTS

Antibody potency was improved 8600-fold, and the target affinity was reached. The refined model predicted pharmacodynamic effects at doses as low as 1 mg kg(-1) and a study in cynomolgus monkeys confirmed in vivo efficacy at 1 mg kg(-1) dosing.

CONCLUSIONS AND IMPLICATIONS

This rational approach to antibody drug discovery enabled the isolation of a potent molecule compatible with chronic, s.c. self-administration by RA patients. We believe this general approach enables the development of optimal biopharmaceuticals.

An engineered Fc variant of an IgG eliminates all immune effector functions via structural perturbations

The Fc variant of IgG2, designated as IgG2σ, was engineered with V234A/G237A /P238S/H268A/V309L/A330S/P331S substitutions to eliminate affinity for Fcγ receptors and C1q complement protein and consequently, immune effector functions. IgG2σ was compared to other previously well-characterized Fc 'muted' variants, including aglycosylated IgG1, IgG2m4 (H268Q/V309L/A330S/P331S, changes to IgG4), and IgG4 ProAlaAla (S228P/L234A/L235A) in its capacity to bind FcγRs and activate various immune-stimulatory responses. In contrast to the previously characterized muted Fc variants, which retain selective FcγR binding and effector functions, IgG2σ shows no detectable binding to the Fcγ receptors in affinity and avidity measurements, nor any detectable antibody-dependent cytotoxicity, phagocytosis, complement activity, or Fc-mediated cytokine release. Moreover, IgG2σ shows minimal immunogenic potential by T-cell epitope analysis. The circulating half-life of IgG2σ in monkeys is extended relative to IgG1 and IgG2, in spite of similar in vitro binding to recombinant FcRn. The three-dimensional structure of the Fc, needed for assessing the basis for the absence of effector function, was compared with that of IgG2 revealing a number of conformational differences near the hinge region of the CH2 domain that result from the amino acid substitutions. Modeling reveals that at least one of the key interactions with FcγRs is disrupted by a conformational change that reorients P329 to a position that prevents it from interacting with conserved W90 and W113 residues of the FcγRs. Inspection of the structure also indicated significant changes to the conformations of D270 and P329 in the CH2 domain that could negatively impact C1q binding. Thus, structural perturbations of the Fc provide a rationale for the loss of function. In toto, these properties of IgG2σ suggest that it is a superior alternative to previously described IgG variants of minimal effector function, for future therapeutic applications of non-immunostimulatory mAb and Fc-fusion platforms.

Reproduction and development of laboratory and wild house dust mites (Acari: Pyroglyphidae) and their relationship to the natural dust ecosystem

Life histories of "wild" house dust mites, Dermatophagoides pteronyssinus (Trouessart) (Acari: Pyroglyphidae), were compared with laboratory cultures by using a diet consisting of skin and dust or a laboratory diet consisting of dried liver and yeast. Under constant conditions of 25 degrees C and 75% RH, fecundity and rate of reproduction were higher in laboratory cultures on both diets compared with wild mites. There were also trends for a shorter prereproductive period and more rapid egg development of laboratory mites compared with wild mites. Overall, there was little effect of diet on either strain of mites at 75% RH. At low RH (64%), fecundity was significantly lower (for both strains on both diets), and there were also trends for longer prereproductive period, reduced rate of reproduction, reduced adult survival, prolonged egg and juvenile development, or a combination compared with 75% RH. Additionally egg and juvenile mortality were significantly higher on the liver and yeast diet. Overall, the skin and dust diet favored both strains of mites at 64% RH. On the liver and yeast diet at 64% RH, wild mite adults performed significantly better than laboratory mites, and egg mortality was lower. These results suggest that laboratory mites have stronger reproduction and development than wild mites, except when under environmental stress and that diet is a significant factor, particularly in suboptimal conditions. This could have important implications for predictive models of house dust mite populations in their natural habitat. Ideally, such models should be developed using data from wild dust mite populations reared on a natural diet.

Cryopreservation of protonemata of Ditrichum cornubicum (paton) comparing the effectiveness of four cryoprotectant pretreatments

If an ex situ programme for the conservation of rare and threatened bryophytes is to succeed, a method of long-term, basal storage is required. The aim of this study was to determine the effectiveness of sucrose, ABA and sucrose/ABA combined, as cryoprotectant pretreatments, for the long-term storage of protonemata of the endangered Cornish path moss, Ditrichum cornubicum. This work is a prelude to the in vitro conservation of rare and endangered UK bryophytes. The addition of sucrose and/or ABA in the pre-culture medium, reduced protonemal growth rate. However, pretreatment afforded a high level of protection against tissue damage during dehydration and freezing, with 100 % regeneration of pretreated plants after thawing, compared to 53 % regeneration of controls. Sucrose combined with ABA in the pre-culture medium gave the most effective cryoprotection, with protonemata having fewer necrotic tissues and rapid recovery of growth.

Hepatitis C virus: prospects for future therapies

Hepatitis C virus (HCV) infection is a major health crisis worldwide. Current treatment requires combination therapy with interferon-alpha and ribavirin. The low efficacy and poor tolerability of this therapeutic regimen has driven the search for safer and more effective medicines. This search has led to intense research efforts which have enhanced our understanding of HCV biology and to the development of a number of strategies for identifying new antiviral agents. At the same time, efforts have been directed towards improving the efficacy and tolerability of existing therapies. Recent developments in the area of modified interferons and research on virus-encoded and host drug discovery targets are reviewed here. Advances in the field of improved interferon-based treatments and the use of new antiviral agents in clinical trials gives cause for optimism in the clinical management of HCV infections.

Medical student career intentions at the Christchurch School of Medicine. The New Zealand Wellbeing, Intentions, Debt and Experiences (WIDE) survey of medical students pilot study. Results part II

AIMS

To record career preferences for medical students at the Christchurch School of Medicine and Health Sciences and investigate factors, including student debt, that might influence career decisions.

METHODS

A questionnaire, The New Zealand Wellbeing, Intentions, Debt, and Experiences (WIDE) Survey of Medical Students, was developed and administered to all 204 medical students at the Christchurch School of Medicine and Health Sciences. The survey included questions relating to preferred career intentions and factors influencing career decisions, including the decision to leave New Zealand to practise medicine.

RESULTS

The response rate was 88%. 80% intend to practise medicine in New Zealand immediately after graduation, however 82% indicated that they would leave within two years of graduation. Financial opportunities overseas and level of debt were the strongest motivating factors to leave. Repayments towards student loans and increased salaries were factors that might retain people in New Zealand. Medical and surgical specialities were the most popular career choices. Personal interest was the strongest motivator for career choice. Practising in a rural community was not popular.

CONCLUSION

Debt is one of a number of important factors influencing medical student career decisions including the decision to leave New Zealand. Initiatives addressing debt may be useful in retaining medical graduates in this country.

Medical student debt at the Christchurch School of Medicine. The New Zealand Wellbeing, Intentions, Debt and Experiences (WIDE) survey of medical students pilot study. Results part I

AIMS

To determine the level and sources of medical student debt at the Christchurch School of Medicine.

METHODS

A questionnaire, The New Zealand Wellbeing, Intentions, Debt, and Experiences (WIDE) Survey of Medical Students, was developed and administered to all 204 medical students at the Christchurch School of Medicine and Health Sciences. Included were questions on student demographics, sources and levels of debt, parental financial support, and student perceptions of their debt.

RESULTS

The response rate was 88%. International students, whose debt was with an overseas government, and students with mortgages were excluded from the data analysis. The combined total debt for the remaining 165 students was $7775000 with $6290000 (81%) owed to the Government Students Loans scheme. One quarter of 6th year medical students had a debt over $83250, 50% had a debt over $70000, and 75% had a debt over $50000. Student allowances were inaccessible to 64% of 4th and 5th year students and part-time employment during term-time was common. Lack of funds was reported to impair full participation in the medical course.

CONCLUSION

The majority of medical students at the Christchurch School of Medicine accumulate high levels of debt, mainly dtrough the Government Student Loans scheme, during their medical training.

The effect of compliance on clinical outcomes for patients with dysphagia on videofluoroscopy

This study investigates clinical outcomes and the degree of compliance in patients who received advice on dysphagia management and the effect of the level of compliance on the incidence of chest infections and aspiration pneumonia, cause of death, and hospital readmission. We performed a retrospective cohort study of 140 patients who had videofluoroscopic studies at Princess Margaret Hospital, Christchurch, New Zealand, from 1 January 1996 to 30 June 1997. The degree to which recommendations on dysphagia management were followed was correlated with the incidence of chest infections, aspiration pneumonia, and readmissions to the hospital. Cause of death, including the contribution of aspiration pneumonia, was assessed by review of medical records and death certificates. Information was available for 89% of the cohort. Twenty-one percent of the survivors never complied with the advice given. Noncompliant subjects were younger (p < 0.05) and more likely to be living at home rather than receiving institutional care (p = 0.05). Noncompliers had more hospital admissions because of chest infections or aspiration pneumonia (22% vs. 1.5%; p < 0.001). Home-dwelling noncompliant subjects received more courses of antibiotics (p < 0.02), but there was no difference in the number of chest infections. Fifty-four people died during the study period. Aspiration pneumonia was recorded as a definite or probable cause of death in 26 (52%) of the 50 subjects for whom reliable information was available and in 6 of 7 subjects who made a deliberate and documented decision not to comply. We conclude that noncompliance with recommendations about dysphagia management is associated with adverse outcomes. There was a high mortality rate and aspiration pneumonia was a common cause of death.

Swallowing problems in the normal ageing population

This study investigated the prevalence of subjectively reported swallowing problems in a group of normal ageing subjects. Twenty-five retirement village residents were included in the sample. A cross-sectional descriptive survey research design was utilised. Data was obtained through the administration of a devised interview schedule. The prevalence of reported swallowing problems in the sample was determined. The nature of the swallowing problems were examined and compared to those reported to occur in the normal ageing population. The utility of the interview schedule was critically evaluated. Results revealed an overall prevalence of 44% of subjects who experience swallowing problems that interfere with their day to day functioning. Of these, 64% experienced swallowing difficulties affecting all phases of the swallow while 36% experienced difficulties affecting the pharyngeal and oesophageal phases. The interview was found to be a useful screening measure in identifying the presence of swallowing problems. The role of the speech pathologist in dysphagia in the normal ageing population is highlighted and justified.

A prospective study of Twin-block appliance therapy assessed by magnetic resonance imaging

Forty children displaying Class II Division 1 malocclusion were involved in a prospective magnetic resonance image investigation to evaluate the effects of Twin-block functional appliances on the temporomandibular joints. None of these children had clinical signs or symptoms of temporomandibular disorders. Nineteen children were treated with a Clark Twin-block appliance for 6 months; the other 21 children received no treatment and served as controls. Comparison between control and Clark Twin-block groups suggested that reduction of the condylar axial angle represents a feature of untreated Class II growth patterns, whereas axial angle stability with Clark Twin-block therapy may suggest alteration of condylar growth direction. Condyles that were positioned at the crest of the articular eminence by the Clark Twin-block at the beginning of treatment had reseated back into the glenoid fossa after 6 months. However, 75% of the condyles were more anteriorly positioned in successfully treated Clark Twin-block cases. There was no clear evidence of remodeling of the glenoid fossa at the eminence as a result of Clark Twin-block treatment. The initial prevalence of disk displacements for the combined groups was 7.5% anterior, 5% medial, and 12.5% for lateral disk displacement. Clark Twin-block therapy had neither positive nor negative effects on disk position, and there was no convincing evidence that the disk was recaptured.

Effects of twin-block therapy on protrusive muscle functions

Protrusive mandibular function, including maximum protrusive force and fatigue time, was investigated in 66 children displaying Class II Division 1 malocclusion. Thirty-two children were treated with the Clark Twin-block appliance and the other 34 children served as untreated controls. The observation period was 6 months. Cross-sectional data based on pretreatment records showed that maximum protrusive force ranged from 18.5 N to 160 N, with a mean of 80.3 +/- 30.7 N. Maximum protrusive force was significantly higher in males than in females (P <.001). The correlation between maximum protrusive force and chronologic age was low (r = 0.20) and did not reach significance. Maximum protrusive force in the group of children with disk displacement was not significantly different from that of the group without disk displacement. Comparison of pretreatment and 6-month records in the untreated control group revealed a significant increase in maximum protrusive force (P <.01) as a result of normal growth, while the measured change in the Twin-block-treated children did not reach significance. Fatiguing the protrusive muscles did not alter mandibular position in the Twin-block group after 6 months of treatment. The present study does not support the lateral pterygoid hypothesis, as there was no evidence of an increase in mandibular protrusive function after treatment with the Twin-block functional appliance.

Multiple meningiomas: case report and review of the literature

A case of a 69 year old woman with multiple meningiomas is presented. Since her first presentation with Jacksonian seizures in 1978, she has had 16 meningiomas excised in seven separate surgical procedures. This is extremely unusual due to both the large number of tumours, and the long period over which they have occurred. We review the epidemiology, possible pathogenesis and genetic associations of this condition.

The predictive value of findings of the common aneuploidies, trisomies 13, 18 and 21, and numerical sex chromosome abnormalities at CVS: experience from the ACC U.K. Collaborative Study. Association of Clinical Cytogeneticists Prenatal Diagnosis Working Party

We report 611 non-mosaic and 91 mosaic findings of trisomies 13, 18 and 21, and numerical sex chromosome abnormalities in a series of 20,527 CVS, in the Association of Clinical Cytogeneticists U.K. Collaborative Study, the majority with analysis of both direct preparations and cultured cells. No false-positive results were encountered among the 611 non-mosaic cases, making these findings a very reliable indicator of the fetal karyotype. One false-negative case was reported. In contrast, the 91 mosaic abnormalities were unreliable predictors of fetal abnormality. Many were associated with normal outcomes, but a significant proportion of cases of each individual aneuploidy proved genuine. Mosaicism for 45,X, and trisomies 13 and 18 was disproportionately common. 17 of the mosaic cases showed complete discordance between the karyotype from direct preparations and that from cultured cells. All would have resulted in either a false-positive or a false-negative finding if only one technique had been used. Based on our experience, and that of others, we believe that the highest level of predictive accuracy using CVS can only be achieved if both direct preparation and cell culture are performed. In addition, we continue to recommend that all pregnancies demonstrating mosaicism for these aneuploidies at CVS undergo amniocentesis or fetal blood sampling to differentiate between confined placental mosaicism and true fetal karyotypic abnormality.

Honeydew sugars and osmoregulation in the pea aphid Acyrthosiphon pisum

Pea aphids, Acyrthosiphon pisum, containing their symbiotic bacteria (untreated aphids) and experimentally deprived of their bacteria by treatment with the antibiotic rifampicin (antibiotic-treated aphids) were reared on the plant Vicia faba. The sugars in the honeydew produced by untreated aphids comprised predominantly the monosaccharides glucose and fructose, while the honeydew of antibiotic-treated aphids contained considerable amounts of oligosaccharides of up to 16 hexose units. The honeydew and haemolymph of the aphids were iso-osmotic, and their osmotic pressure was significantly lower in untreated aphids (0.91&shy;0.95 MPa) than in antibiotic-treated aphids (1.01&shy;1.05 MPa) (P&lt;0.05). For insects reared on chemically defined diets containing 0.15&shy;1.0 mol l-1 sucrose (osmotic pressure 1.1&shy;4.0 MPa), the osmotic pressure of the aphid haemolymph did not vary with dietary osmotic pressure, but was regulated to approximately 1.0 MPa in untreated and 1.3 MPa in antibiotic-treated aphids. The sugars in the aphid honeydew varied with dietary sucrose concentration; with monosaccharides dominant at low concentrations and oligosaccharides dominant at high concentrations of dietary sucrose. The lowest dietary sucrose concentration at which honeydew oligosaccharides were detected was 0.2 mol l-1 for the antibiotic-treated aphids and 0.3 mol l-1 for untreated aphids. These data indicate that the aphid, and not its associated microbiota, mediates the synthesis of oligosaccharides when the osmotic pressure of the ingesta is high.

Correlations between anatomic and MRI sections of human cadaver temporomandibular joints in the coronal and sagittal planes

Cadaver material was used in this study to correlate sequential sagittal and coronal T1-weighted magnetic resonance images against anatomic detail. Magnetic resonance imaging (MRI) was found to accurately represent soft tissues in normal and deranged joints. In contrast to previous reports, MRI was found to accurately represent the discal-retrodiscal junction and did not appear to give false positive findings for disc displacement. Magnetic resonance imaging provided good images of bony outline, particularly in coronal views. Difficulties in interpretation arose when different adjoining tissues produced the same MR image; the central tendon of the lateral pterygoid muscle can appear as an extension of the disc, imaging as a distorted and displaced disc. In anatomic sections, a medial hernia sac in the lower joint space was seen as a constant indicator of the medial component of disc displacement; however, this was not evident in sagittal and coronal T1-weighted images. Fibrocartilaginous remodeling of the articular surface projecting into a discal perforation presented the same image as normal discal tissue. Because discs are often thinned over the lateral pole, it is difficult to determine whether discal tissue is present between the articular surfaces when MRI is at its present resolution. Subcortical bone spaces may be misinterpreted as areas of avascular necrosis and osteochondritis dissecans. It is recommended that an imaging sequence of the TMJ include a midcondyle image and lateral, central, and medial sagittal images; however, the lateral sagittal image is the most difficult to interpret.

Marked enrichment of the alkenylacyl subclass of plasma ethanolamine glycerophospholipid with eicosapentaenoic acid in human subjects consuming a fish oil concentrate

Alteration in human platelet fatty acid levels with the consumption of fish oils containing eicosapentaenoic acid (EPA, 20:5n-3) and docosahexaenoic acid (DHA, 22:6n-3) have been well documented, but changes in the fatty acid composition of plasma plasmalogenic phospholipid under similar circumstances have not been delineated. In the present study, subjects consumed the fish oil concentrate (MaxEPA) for 6 wk followed immediately by a 6-wk recovery period with no fish oil ingestion. Plasma total choline glycerophospholipid (GPC) and ethanolamine glycerophospholipid (GPE) subclasses isolated from blood samples obtained at 0, 3, 6, 9 and 12 wk of the experimental period were analyzed for fatty acid composition via thin-layer and gas-liquid chromatographic techniques. Consumption of fish oil for 3 or 6 wk significantly elevated the content of n-3 fatty acids while concomitantly decreasing n-6 fatty acid levels in plasma total GPC and in diacyl and alkenylacyl (plasmalogen) GPE. Alkenylacyl GPE exhibited the greatest alteration of both n-3 and n-6 fatty acid levels. Following 6 wk of supplementation with fish oil, EPA rose by 24.6 mol% in alkenylacyl GPE compared to increases of 6.7 and 7.1 mol% in diacyl GPE and total GPC, respectively. The increase in EPA (from 5.0 to 29.6 mol%) in plasma alkenylacyl GPE represents amongst the highest enrichment of EPA in any lipid yet reported in human subjects. DHA also rose by 8.0, 4.8, and 3.1 mol% in alkenylacyl GPE, diacyl GPE, and total GPC, respectively. Alkenylacyl GPE exhibited the greatest mol% decline (by 18.7 mol%) in arachidonic acid (AA, 20:4n-6) following 6 wk of fish oil supplementation. The corresponding decreases of AA in diacyl GPE and total GPC were 8.7 and 1.8 mol%, respectively. Following the 6 wk recovery period, n-3 and n-6 fatty acid levels had returned to pre-supplementation values. The marked enrichment of alkenylacyl GPE in n-3 fatty acids, especially EPA, may be of significance with respect to a unique role for this plasma phospholipid subclass in attenuating certain lipoprotein-mediated cardiovascular effects as observed with fish/fish oil consumption.

Complex formation between the NS3 serine-type proteinase of the hepatitis C virus and NS4A and its importance for polyprotein maturation

Processing of the hepatitis C virus polyprotein is mediated by host cell signalases and at least two virally encoded proteinases. Of these, the serine-type proteinase encompassing the amino-terminal one-third of NS3 is responsible for cleavage at the four sites carboxy terminal of NS3. The activity of this proteinase is modulated by NS4A, a 54-amino-acid polyprotein cleavage product essential for processing at the NS3/4A, NS4A/4B, and NS4B/5A sites and enhancing cleavage efficiency between NS5A and NS5B. Using the vaccinia virus-T7 hybrid system to express hepatitis C virus polypeptides in BHK-21 cells, we studied the role of NS4A in proteinase activation. We found that the NS3 proteinase and NS4A form a stable complex when expressed as a single polyprotein or as separate molecules. Results from deletion mapping show that the minimal NS4A domain required for proteinase activation is located in the center of NS4A between amino acids 1675 and 1686 of the polyprotein. Amino acid substitutions within this domain destabilizing the NS3-NS4A complex also impair trans cleavage at the NS4A-dependent sites. Similarly, deletion of amino-terminal NS3 sequences impairs complex formation as well as cleavage at the NS4B/5A site but not at the NS4A-independent NS5A/5B site. These results suggest that a stable NS3-NS4A interaction is important for cleavage at the NS4A-dependent sites and that amino-terminal NS3 sequences and the central NS4A domain are directly involved in complex formation.