How I maximised my training during the COVID-19 pandemic

The COVID-19 pandemic was declared in March 2020 and London maternity units were among the first in the United Kingdom to report maternal infection and vertical transmission. To manage resources, over half of all Obstetrics and Gynaecology trainees were redeployed to support front-line specialities such as Core Medicine and Accident and Emergency. The vignettes in this article illustrate how three trainees maximised their limited training opportunities in the face of exceptional disruption, lack of surgical training opportunities and workload pressures.

Obstetric outcomes in Jehovah's Witnesses: case series over nine years in a London teaching hospital

OBJECTIVES

The aim of the study is to assess obstetric and fetal outcomes of Jehovah's Witnesses (JWs) mothers in an inner city teaching hospital, as well as to examine the acceptance rates of various blood fractions and blood transfusion alternatives.

METHODS

Case series to evaluate the maternal and fetal outcomes of JWs over a nine period between 2013 and 2021.

RESULTS

There were 146 pregnancies extracted from our database, of which 10 were early pregnancy losses. Data from 136 deliveries > 24 weeks' gestation were assessed, with a mean maternal age and gestational age of 30.26 (± 5.4) years and 38.7 (± 5.3) weeks, respectively. 57% had normal vaginal deliveries, 8% had instrumental births and 35% had caesarean births. Mean estimated blood loss at caesarean was 575 (± 305.6) mls, while the overall mean estimated loss was 427.8 (± 299.8) mls. Cell salvage was performed in all caesarean sections but autologous transfusion was only necessary for 26%. Consultant presence was documented in 62% of caesarean births. The mean birthweight and 5-min Apgar scores were 3.31 (± 0.05) kg and 9.1 (± 0.09), respectively. There were no maternal deaths or admissions to the adult intensive care unit and the most serious complication was a uterine rupture following a trial of scar, after which the baby required cooling for hypoxic ischaemic encephalopathy.

CONCLUSIONS

Pregnant JWs received obstetric care led by senior clinicians, with optimisation of haematinics, minimizing of blood loss at delivery and access to technology such as cell salvage.

The Importance of Consumer Authorities for the Production and Maintenance of Trust and Social Capital in Consumer Markets

Trust is a valuable resource that varies between countries. This paper suggests that consumers' trust in retailers and service providers, facilitating interactions and transactions between sellers and buyers in impersonal markets, is best understood as generalized trust. The paper is based on 28 037 respondents' evaluations of consumer conditions in 30 European countries. The material reveals large country-to-country variations in the percentages of residents who trust public authorities to protect their consumer rights. Moreover, there are large differences in the percentages who trust retailers and service providers to respect their rights as consumers. A multilevel path analysis supports the paper's main hypothesis that fair and effective consumer authorities enhance generalized trust in the markets. The analyses also demonstrate that fair and effective consumer institutions contribute to more equality in the markets. It is argued that consumer markets are important arenas for the maintenance and production of trust and social capital. And that generalized trust produced in markets will probably extend to, and be valuable for, the wider society.

The management of women with thoracic endometriosis: a national survey of British gynaecological endoscopists

OBJECTIVES

This study evaluates current national opinions on screening, diagnosis, and management of thoracic endometriosis.

BACKGROUND

Thoracic endometriosis is a rare but serious condition with four main clinical presentations: pneumothorax, haemoptysis, haemothorax, and pulmonary nodules. There are no specialist centres in the United Kingdom despite growing patient desire for recognition, investigation, and treatment.

METHODS

We distributed a multiple-choice email survey to senior members of the British Society for Gynaecological Endoscopy. Descriptive statistics were used to present the results. Results: We received 67 responses from experienced clinicians having provided over 800 combined years of endometriosis patient care. The majority of respondents managed over 100 endometriosis patients annually, for more than five years. Over one third had never managed a patient with symptomatic thoracic endometriosis; just 9% had managed more than 30 cases over the course of their career. Screening varied by modality with only 4% of clinicians always taking a history of respiratory symptoms while 69% would always screen for diaphragmatic endometriosis during laparoscopy. The management of symptomatic thoracic endometriosis varied widely with the commonest treatment being surgery followed by hormonal therapies. Regarding management, 71% of respondents felt the team should comprise of four or more different specialists, and 56% believed care should be centralised either regionally or nationally.

CONCLUSIONS

Thoracic endometriosis is poorly screened for amongst clinicians with varied management lacking a common diagnostic or therapeutic pathway in the United Kingdom. Specialists expressed a preference for women to be managed in a large multidisciplinary team setting at a regional or national level.

Labour market marginalisation in young refugees with and without common mental disorders

Background

This study explored how inequality in labour market marginalisation (LMM) between refugees and their peers developed during early adulthood in Denmark and Sweden (DK/SE), and the role of common mental disorders (CMD) in these trends.

Methods

Using registry data, all refugees living in DK/SE in 2009-2012 who were born 1986-1993 and who immigrated as children (aged 0-17) were included (N = 13,390/45,687) and 1:5 matched on age, sex and municipality size to individuals born in DK/SE with at least one parent also born in DK/SE (N = 69,650/227,287). Information on psychiatric care (hospital and medicine) during 2009-2011 indicated CMD, while LMM was measured during 2012-2015 using income-based indicators. Probabilities of LMM were standardized by multiplying the estimated parameters of linear probability models in SE (adjusted for age, sex, municipality size, age of arrival, origin country, and accompanying family) onto the mean of the covariates in DK.

Results

The risk of LMM was 2-2.5 times higher for refugees across ages 20-29 in DK/SE. The risk tended to decrease in SE but increased in DK for refugees. The increase was accentuated for youth with CMD. However, CMD did not explain the inequality between refugee and majority youth. The increase in DK was driven by birth-cohort differences, while the trend in SE was consistent across birth cohorts.

Conclusions

CMD did not capture the vulnerability that sets refugees apart from their peers. While immigration and integration policy differences between DK and SE increased, the integration outcomes diminished, suggesting the importance of factors other than national level policies.

Key messages

Young refugees in DK/SE were more at risk of labour market marginalization than their majority peers. Healthcare contact for common mental disorders raised levels, but did not reduce inequalities. Labour market marginalisation decreased with age in Sweden but increased for refugees in Denmark, driven by birth cohort difference.

Psychiatric care utilization among children in refugee families – a Swedish population-based study

Background

Previous studies have demonstrated a high prevalence of mental health problems, in particular depression, anxiety, and posttraumatic stress disorder (PTSD), among individuals with experiences of war, persecution, and torture. Mental health problems can affect parenting and the well-being of the children. However, few large-scale studies have investigated the intergenerational effects of psychological trauma on children in refugee families.

Methods

Register data on all children living in Stockholm, Sweden, in 2016 (>90 000) were used to investigate utilization of child and adolescent psychiatric care in relation to parental PTSD, in foreign-born and Swedish-born refugee children compared to non-refugee children.

Results

In total, 13% of children in refugee families had a parent who had been treated for PTSD. Preliminary results showed an increased risk of psychiatric care use among foreign-born refugee children (HR: 2.68, 95% CI: 2.08-3.44) and in Swedish-born children in refugee families (HR: 1.86, 95% C.I: 1.43-2.41), whose mothers had been treated for PTSD. No association was observed in relation to PTSD diagnoses in fathers.

Conclusions

The findings indicate that refugee children with experience of PTSD of the mother were more than twice as likely to have been in contact with child and adolescent psychiatric services. This underlines the importance of making mental health care available so that adequate support and treatment is offered to refugees and their children.

Key messages

This study contributes with important information on the intergenerational effects of psychological trauma in refugee families. In order to prevent mental health problems in refugee children, Public health interventions for their parents with PTSD are crucial.

Childhood bereavement and adult mortality: A 65-year follow-up of the Stockholm birth cohort

About 3% of children in Sweden, 4-5% in the UK, and 5% in the US experience the death of a parent during childhood. The event is highly unexpected and stressful and could have long-term social and health consequences across the life course. To alleviate grief, bereaved children may engage in health-damaging behaviours such as smoking, alcohol or drug abuse, violence, delinquency and risky sexual behaviour. Few studies have been able to study health consequences by childhood parental loss and mechanisms explaining associations across the life course. Using the Stockholm Birth Cohort Study (SBC), including all children born in 1953 in the metropolitan Stockholm area, we examined whether childhood bereavement is associated with all-cause mortality until age 63 and whether various pathways (e.g. economic, behavioral and social circumstances) account for the association. 15,117 individuals were followed between 1953 and 2018 using survey data and national registry data. We used Cox proportional hazard regression and mediation analysis for survival analysis to decompose direct and indirect effects. The death of a parent was associated with 40 to 50% elevated risk of mortality in offspring, and the association was mediated through delinquent behaviour in adolescence and income in adulthood especially for male offspring. Our findings suggest that parental loss has a life long impact on the mortality risk of bereaved children and that interventions targeting delinquency and socio-economic circumstances in bereaved children could be successful in reducing their excess mortality risk.

Key messages

Bereavement in childhood has a life-long impact on health. Interventions targeting delinquency and socio-economic circumstances could be successful in reducing the excess mortality risk.

Health-promoting factors in higher education for a sustainable working life - protocol for a multicenter longitudinal study

BACKGROUND

The World Health Organization has highlighted the importance of health promotion for health service providers in order to ensure sustainable working life for individuals involved in providing health services. Such sustainability begins when students are preparing to manage their own future health and welfare in working life. It has been suggested that universities, employees and trainee health professionals should adopt or follow a salutogenic approach that not only complements the providing of information on known health risks but also favors health promotion strategies. This paper describes the study design and data collection methods in a planned study aiming to explore health-promoting factors for a sustainable working life among students in higher education within healthcare and social work.

METHODS

This protocol describes a multicenter longitudinal study involving Swedish students on higher education programs in the healthcare and social work sectors. In 2018, the study invited students on seven education programs at six universities to participate. These programs were for qualification as: biomedical laboratory scientists (n = 121); dental hygienists (n = 87); nurses (n = 1411); occupational therapists (n = 111); physiotherapists (n = 48); radiographers (n = 60); and, social workers (n = 443). In total, 2283 students were invited to participate. Participants completed a baseline, a self-reported questionnaire including six validated instruments measuring health-promoting factors and processes. There are to be five follow-up questionnaires. Three while the students are studying, one a year after graduating, and one three years after graduating. Each questionnaire captures different health-promoting dimensions, namely: health-promoting resources (i.e. sense of coherence); occupational balance; emotional intelligence; health and welfare; social interaction; and work and workplace experiences/perceptions.

DISCUSSION

This study focuses on the vastly important aspect of promoting a sustainable working life for healthcare and social work employees. In contrast to previous studies in this area, the present study uses different, validated instruments in health promotion, taking a salutogenic approach. It is hoped that, by stimulating the implementation of new strategies, the study's findings will lead to education programs that prepare students better for a sustainable working life in healthcare and social work.

Structure of a prereaction complex between the nerve agent sarin, its biological target acetylcholinesterase, and the antidote HI-6

Organophosphorus nerve agents interfere with cholinergic signaling by covalently binding to the active site of the enzyme acetylcholinesterase (AChE). This inhibition causes an accumulation of the neurotransmitter acetylcholine, potentially leading to overstimulation of the nervous system and death. Current treatments include the use of antidotes that promote the release of functional AChE by an unknown reactivation mechanism. We have used diffusion trap cryocrystallography and density functional theory (DFT) calculations to determine and analyze prereaction conformers of the nerve agent antidote HI-6 in complex with Mus musculus AChE covalently inhibited by the nerve agent sarin. These analyses reveal previously unknown conformations of the system and suggest that the cleavage of the covalent enzyme-sarin bond is preceded by a conformational change in the sarin adduct itself. Together with data from the reactivation kinetics, this alternate conformation suggests a key interaction between Glu202 and the O-isopropyl moiety of sarin. Moreover, solvent kinetic isotope effect experiments using deuterium oxide reveal that the reactivation mechanism features an isotope-sensitive step. These findings provide insights into the reactivation mechanism and provide a starting point for the development of improved antidotes. The work also illustrates how DFT calculations can guide the interpretation, analysis, and validation of crystallographic data for challenging reactive systems with complex conformational dynamics.

Hepatitis E virus infection and acute-on-chronic liver failure in West Africa: a case-control study from The Gambia

BACKGROUND

In sub-Saharan Africa, it is unknown whether hepatitis E virus (HEV) infection is a common precipitating event of acute-on-chronic liver failure (ACLF).

AIMS

To estimate the prevalence of HEV infection in general population and assess whether HEV is a common trigger of ACLF in cirrhotic patients in The Gambia, West Africa.

METHODS

We first conducted an HEV sero-survey in healthy volunteers. We then tested cirrhotic patients with ACLF (cases) and compensated cirrhosis (controls) for anti-HEV IgG as a marker of exposure to HEV, and anti-HEV IgA and HEV RNA as a marker of recent infection. We also described the characteristics and survival of the ACLF cases and controls.

RESULTS

In the healthy volunteers (n = 204), 13.7% (95% CI: 9.6-19.2) were positive for anti-HEV IgG, and none had positive HEV viraemia. After adjusting for age and sex, the following were associated with positive anti-HEV IgG: being a Christian, a farmer, drinking water from wells, handling pigs and eating pork. In 40 cases (median age: 45 years, 72.5% male) and 71 controls (39 years, 74.6% male), ≥70% were infected with hepatitis B virus. Although hepatitis B flare and sepsis were important precipitating events of ACLF, none had marker of acute HEV. ACLF cases had high (70.0%) 28-day mortality.

CONCLUSIONS

Hepatitis E virus infection is endemic in The Gambia, where both faecal-oral route (contaminated water) and zoonotic transmission (pigs/pork meat) may be important. However, acute HEV was not a common cause of acute-on-chronic liver failure in The Gambia.

Benefits of statistical molecular design, covariance analysis, and reference models in QSAR: a case study on acetylcholinesterase

Scientific disciplines such as medicinal- and environmental chemistry, pharmacology, and toxicology deal with the questions related to the effects small organic compounds exhort on biological targets and the compounds' physicochemical properties responsible for these effects. A common strategy in this endeavor is to establish structure-activity relationships (SARs). The aim of this work was to illustrate benefits of performing a statistical molecular design (SMD) and proper statistical analysis of the molecules' properties before SAR and quantitative structure-activity relationship (QSAR) analysis. Our SMD followed by synthesis yielded a set of inhibitors of the enzyme acetylcholinesterase (AChE) that had very few inherent dependencies between the substructures in the molecules. If such dependencies exist, they cause severe errors in SAR interpretation and predictions by QSAR-models, and leave a set of molecules less suitable for future decision-making. In our study, SAR- and QSAR models could show which molecular sub-structures and physicochemical features that were advantageous for the AChE inhibition. Finally, the QSAR model was used for the prediction of the inhibition of AChE by an external prediction set of molecules. The accuracy of these predictions was asserted by statistical significance tests and by comparisons to simple but relevant reference models.

Hydroxyethylene isosteres introduced in type II collagen fragments substantially alter the structure and dynamics of class II MHC Aq/glycopeptide complexes

Introduction of hydroxyethylene isosteres into glycopeptides led to loss of Aq affinity and subsequent T cell response due to disruption of hydrogen bond networks.

Diabetes management in Swedish schools: a national survey of attitudes of parents, children, and diabetes teams

BACKGROUND

Parents of children with type 1 diabetes often raise complaints about self-care support during school time. The aim of this study was to investigate attitudes to diabetes care in school reported by children with type 1 diabetes, their parents, and their diabetes teams.

METHODS

Children who had completed preschool class or at least one grade in the 9-yr compulsory school system were invited to participate. Data were collected using separate questionnaires for the children and their parents. In addition, the members of the diabetes team answered a separate questionnaire. All pediatric diabetes centers in Sweden were invited to participate in the study.

RESULTS

All Swedish children and adolescents with diabetes are treated at pediatric diabetes centers. Out of 44 eligible centers, 41 were able to participate. The questionnaires were completed by 317 children and adolescents and 323 parents. The mean age was 11.4 ± 2.7 yr and hemoglobin A1c (HbA1c) was 61.8 ± 12.4 mmol/mol (7.8 ± 1.1%). For 57% of the children, there was no member of staff at the school with principal responsibility to support diabetes self-care. A written action plan for hypoglycemia existed for 60% of the children. Twenty-one percent of the parents regularly gave less insulin than they calculated would be needed at breakfast because of fear of hypoglycemia during school time.

CONCLUSIONS

Although Sweden has legislation underlining the specific need for diabetes care in school, this nationwide study demonstrates deficiencies in the support of self-care management.

Preliminary evidence that early reduction in p11 levels in natural killer cells and monocytes predicts the likelihood of antidepressant response to chronic citalopram

The prediction of treatment response in many neuropsychiatric disorders would be facilitated by easily accessible biomarkers. Using flow cytometry, we herein demonstrate correlations between early reductions of p11 levels in Natural Killer (NK) cells and monocytes and antidepressant response to citalopram in patients with major depressive disorder (MDD).

Students' learning as the focus for shared involvement between universities and clinical practice: a didactic model for postgraduate degree projects

In an academic programme, completion of a postgraduate degree project could be a significant means of promoting student learning in evidence- and experience-based practice. In specialist nursing education, which through the European Bologna process would be raised to the master's level, there is no tradition of including a postgraduate degree project. The aim was to develop a didactic model for specialist nursing students' postgraduate degree projects within the second cycle of higher education (master's level) and with a specific focus on nurturing shared involvement between universities and healthcare settings. This study embodies a participatory action research and theory-generating design founded on empirically practical try-outs. The 3-year project included five Swedish universities and related healthcare settings. A series of activities was performed and a number of data sources secured. Constant comparative analysis was applied. A didactic model is proposed for postgraduate degree projects in specialist nursing education aimed at nurturing shared involvement between universities and healthcare settings. The focus of the model is student learning in order to prepare the students for participation as specialist nurses in clinical knowledge development. The model is developed for the specialist nursing education, but it is general and could be applicable to various education programmes.

Targeting acetylcholinesterase: identification of chemical leads by high throughput screening, structure determination and molecular modeling

Acetylcholinesterase (AChE) is an essential enzyme that terminates cholinergic transmission by rapid hydrolysis of the neurotransmitter acetylcholine. Compounds inhibiting this enzyme can be used (inter alia) to treat cholinergic deficiencies (e.g. in Alzheimer's disease), but may also act as dangerous toxins (e.g. nerve agents such as sarin). Treatment of nerve agent poisoning involves use of antidotes, small molecules capable of reactivating AChE. We have screened a collection of organic molecules to assess their ability to inhibit the enzymatic activity of AChE, aiming to find lead compounds for further optimization leading to drugs with increased efficacy and/or decreased side effects. 124 inhibitors were discovered, with considerable chemical diversity regarding size, polarity, flexibility and charge distribution. An extensive structure determination campaign resulted in a set of crystal structures of protein-ligand complexes. Overall, the ligands have substantial interactions with the peripheral anionic site of AChE, and the majority form additional interactions with the catalytic site (CAS). Reproduction of the bioactive conformation of six of the ligands using molecular docking simulations required modification of the default parameter settings of the docking software. The results show that docking-assisted structure-based design of AChE inhibitors is challenging and requires crystallographic support to obtain reliable results, at least with currently available software. The complex formed between C5685 and Mus musculus AChE (C5685•mAChE) is a representative structure for the general binding mode of the determined structures. The CAS binding part of C5685 could not be structurally determined due to a disordered electron density map and the developed docking protocol was used to predict the binding modes of this part of the molecule. We believe that chemical modifications of our discovered inhibitors, biochemical and biophysical characterization, crystallography and computational chemistry provide a route to novel AChE inhibitors and reactivators.

Characterization of long-term mixed donor-donor chimerism after double cord blood transplantation

Double cord blood transplantation (DCBT) with two matched or partially matched cord blood units has been implemented successfully to circumvent the limitations of graft cell dose associated with single CBT. After DCBT, sustained haematopoiesis is derived almost exclusively from only one of the donated units. None the less, we previously observed two of six evaluable DCBT patients still having mixed donor-donor chimerism at 28 and 45 months post-transplantation, respectively. In the present study we utilize flow cytometry techniques to perform the first thorough analysis of phenotype and functionality of cord blood units in patients with mixed donor-donor chimerism. Our results suggest that the two stable cord blood units are different phenotypically and functionally: one unit shows more naive T cells, lower T cell cytokine production and higher frequencies of natural killer cells, the other shows higher frequencies of well-differentiated and functional lymphocytes. Additionally, in comparison with control patients having a single prevailing cord blood unit, the patients with donor-donor chimerism exhibit less overall T cell cytokine production and a smaller fraction of memory T cells. Furthermore, our results indicate that human leucocyte antigen-C match of donor units may partly explain the development of a donor-donor mixed chimerism.

Herpes simplex virus infection downmodulates NKG2D ligand expression

Herpes simplex virus (HSV) type 1 infection may cause orofacial infections in humans. The virus resides in a latent form in neural ganglia and occasionally reactivates and infects epithelial cells. Natural killer (NK) cells have been implicated in immune control of herpes virus infections, possibly by downmodulating major histocompatibility complex (MHC) class I and by other, as yet unidentified, mechanisms. Upon HSV-1 infection of cell lines, surface levels of NKG2D ligands MHC class I related proteins (MIC) A and UL16 binding protein 2 were downmodulated due to late viral gene product(s). As also MHC class I levels were reduced by HSV-1, NK cell recognition of HeLa cells was not affected by infection. Total cellular MICA contents remained unchanged, suggesting masking, internalization or intracellular retention of MICA as possible mechanisms of viral downregualtion of MICA surface levels. Furthermore, NK cells from patients with active HSV-1 infection had a tendency towards increased expression level of the activating receptor NKG2D. These data support a role for NKG2D-MICA interactions in immune responses to HSV-1 reactivation.

Leishmania surface protein gp63 binds directly to human natural killer cells and inhibits proliferation

Natural killer (NK) cells contribute to immunity as the first line of defence in numerous infections by early cytokine secretion and cytotoxicity. In Leishmania infection, NK cells contribute with interferon-gamma and may assist in directing the immune response towards T helper type 1, which is essential for successful control of the parasites. Thus, NK cells may play an important role in both resistance and control of the infection. However, during Leishmania infection NK cells show signs of suppression. To explore the reason for this suppression, we exposed naive and interleukin (IL)-2 activated NK cells directly to promastigotes of Leishmania major in vitro. As a rapid consequence of contact between naive NK cells and promastigotes, expression of NK cell receptors show significant changes. We identify one of the major surface molecules of promastigotes, glycoprotein (gp) 63, as an important agent for these suppressive effects by using promastigotes of a gp63ko strain of L. major. Furthermore, proliferation of IL-2-activated purified NK cells is suppressed after exposure to the wild-type but not to gp63ko promastigotes. However, gp63ko L. major induced no NK cell proliferation when NK cells were co-cultured with peripheral blood mononuclear cells populations such as CD14(+) monocytes or T cells.

Blood oxygen depletion during rest-associated apneas of northern elephant seals (Mirounga angustirostris)

Blood gases (P(O)2, P(CO)2, pH), oxygen content, hematocrit and hemoglobin concentration were measured during rest-associated apneas of nine juvenile northern elephant seals. In conjunction with blood volume determinations, these data were used to determine total blood oxygen stores, the rate and magnitude of blood O(2) depletion, the contribution of the blood O(2) store to apneic metabolic rate, and the degree of hypoxemia that occurs during these breath-holds. Mean body mass was 66+/-9.7 kg (+/- s.d.); blood volume was 196+/-20 ml kg(-1); and hemoglobin concentration was 23.5+/-1.5 g dl(-1). Rest apneas ranged in duration from 3.1 to 10.9 min. Arterial P(O)2 declined exponentially during apnea, ranging between a maximum of 108 mmHg and a minimum of 18 mmHg after a 9.1 min breath-hold. Venous P(O)2 values were indistinguishable from arterial values after the first minute of apnea; the lowest venous P(O)2 recorded was 15 mmHg after a 7.8 min apnea. O(2) contents were also similar between the arterial and venous systems, declining linearly at rates of 2.3 and 2.0 ml O(2) dl(-1) min(-1), respectively, from mean initial values of 27.2 and 26.0 ml O(2) dl(-1). These blood O(2) depletion rates are approximately twice the reported values during forced submersion and are consistent with maintenance of previously measured high cardiac outputs during rest-associated breath-holds. During a typical 7-min apnea, seals consumed, on average, 56% of the initial blood O(2) store of 52 ml O(2) kg(-1); this contributed 4.2 ml O(2) kg(-1) min(-1) to total body metabolic rate during the breath-hold. Extreme hypoxemic tolerance in these seals was demonstrated by arterial P(O)2 values during late apnea that were less than human thresholds for shallow-water blackout. Despite such low P(O)2s, there was no evidence of significant anaerobic metabolism, as changes in blood pH were minimal and attributable to increased P(CO)2. These findings and the previously reported lack of lactate accumulation during these breath-holds are consistent with the maintenance of aerobic metabolism even at low oxygen tensions during rest-associated apneas. Such hypoxemic tolerance is necessary in order to allow dissociation of O(2) from hemoglobin and provide effective utilization of the blood O(2) store.

The bovine papillomavirus replicon

The bovine papillomavirus genome contains two cis-acting sequences which can serve as signals for replication. At least three virally encoded genes seem to be involved in plasmid replication: E6, E6/7 and E1. Mutations in either the E6 or the E7 open reading frame create plasmids that are maintained at a low copy number per cell. Mutations in the E1 open reading frame are absolutely lethal to replication. Complementation experiments show that these mutations define separate genes. Experiments are described which show that cells harbouring plasmids with mutations in either the E6 or the E7 open reading frame acquire an immunity to high copy-number plasmids. We suggest that either the cell or the virus encodes a repressor. The positive action of E6 and E6/7 modulates the activity of this repressor to allow for the high copy-number state. Though the viral oncogenes are capable of transforming cells separately when they are expressed as part of certain recombinant DNA expression systems, it is clear that, in the context of the entire viral replicon, interactions between the transforming functions and replication functions must exist.

The expression of human natural killer cell receptors in early life

Natural killer (NK) cells play an important role in tumour immunosurveillance and the early defence against viral infections. Recognition of altered cells (i.e. infected- or tumour-cells) is achieved through a multiple receptor recognition strategy which gives the NK cells inhibitory or activating signals depending on the ligands present on the target cell. NK cells originate from the bone marrow where they develop and proliferate. However, further maturation processes and homeostasis of NK cells in peripheral blood are not well understood. To determine the proportions of cells and the expression of NK cell receptors, mononuclear cells from children at three time points during early childhood were compared, i.e. cord blood (CB), 2 and 5 years of age. The proportion of NK cells was high in CB, but the interferon-gamma (IFN-gamma) production low compared to later in life. In contrast, the proportion of T cells was low in CB. This may indicate a deviation of the regulatory function of NK cells in CB compared to later in life, implying an importance of innate immunity in early life before the adaptive immune system matures. Additionally, we found that the proportion of LIR-1(+) NK cells increased with increasing age while CD94(+)NKG2C(-) (NKG2A(+)) NK cells and the level of expression of NKG2D, NKp30 and NKp46 decreased with age. These age related changes in NK cell populations defined by the expression of activating and inhibitory receptors may be the result of pathogen exposure and/or a continuation of the maturation process that begins in the bone marrow.

Intravascular pressure profiles in elephant seals: Hypotheses on the caval sphincter, extradural vein and venous return to the heart

In order to evaluate hemodynamics in the complex vascular system of phocid seals, intravascular pressure profiles were measured during periods of rest-associated apnea in young elephant seals (Mirounga angustirostris). There were no significant differences between apneic and eupneic mean arterial pressures. During apnea, venous pressure profiles (pulmonary artery, thoracic portion of the vena cava (thoracic vena cava), extradural vein, and hepatic sinus) demonstrated only minor, transient fluctuations. During eupnea, all venous pressure profiles were dominated by respiratory fluctuations. During inspiration, pressures in the thoracic vena cava and extradural vein decreased -9 to -21 mm Hg, and -9 to -17 mm Hg, respectively. In contrast, hepatic sinus pressure increased 2-6 mm Hg during inspiration. Nearly constant hepatic sinus and intrathoracic vascular pressure profiles during the breath-hold period are consistent with incomplete constriction of the caval sphincter during these rest-associated apneas. During eupnea, negative inspiratory intravascular pressures in the chest ("the respiratory pump") should augment venous return via both the venae cavae and the extradural vein. It is hypothesized that, in addition to the venae cavae, the prominent para-caval venous system of phocid seals (i.e., the extradural vein) is necessary to allow adequate venous return for maintenance of high cardiac outputs and blood pressure during eupnea.

Cardiac output and muscle blood flow during rest-associated apneas of elephant seals

In order to evaluate hemodynamics and blood flow during rest-associated apnea in young elephant seals (Mirounga angustirostris), cardiac outputs (CO, thermodilution), heart rates (HR), and muscle blood flow (MBF, laser Doppler flowmetry) were measured. Mean apneic COs and HRs of three seals were 46% and 39% less than eupneic values, respectively (2.1+/-0.3 vs. 4.0+/-0.1 mL kg(-1) s(-1), and 54+/-6 vs. 89+/-14 beats min(-1)). The mean apneic stroke volume (SV) was not significantly different from the eupneic value (2.3+/-0.2 vs. 2.7+/-0.5 mL kg(-1)). Mean apneic MBF of three seals was 51% of the eupneic value. The decline in MBF during apnea was gradual, and variable in both rate and magnitude. In contrast to values previously documented in seals during forced submersions (FS), CO and SV during rest-associated apneas were maintained at levels characteristic of previously published values in similarly-sized terrestrial mammals at rest. Apneic COs of such magnitude and incomplete muscle ischemia during the apnea suggest that (1) most organs are not ischemic during rest-associated apneas, (2) the blood O(2) depletion rate is greater during rest-associated apneas than during FS, and (3) the blood O(2) store is not completely isolated from muscle during rest-associated apneas.

NK cells in autoimmune disease

The role of NK cells in autoimmunity has not been extensively studied. Speaking for a disease-promoting role for NK cells in autoimmune diseases are recent results suggesting that IFN-gamma production by NK cells may help adaptive immune responses diverge in the direction of a Th1 response. NK cells may also be involved in direct killing of tissue cells, which could lead to acceleration of autoimmunity. However, NK cells have also been shown to protect from some autoimmune diseases. A possible reason for this discrepancy may lie in the capacity of NK cells also to produce Th2 cytokines, which could downregulate the Th1 responses that are common in autoimmune disorders. Thus there is at present no coherent view on the role of NK cells in autoimmunity, and more work is needed to clarify why NK cells in some cases aggravate disease and in some cases protect from disease.