The neurodevelopmental trajectory of beta band oscillations: an OPM-MEG study

Neural oscillations mediate the coordination of activity within and between brain networks, supporting cognition and behaviour. How these processes develop throughout childhood is not only an important neuroscientific question but could also shed light on the mechanisms underlying neurological and psychiatric disorders. However, measuring the neurodevelopmental trajectory of oscillations has been hampered by confounds from instrumentation. In this paper, we investigate the suitability of a disruptive new imaging platform - Optically Pumped Magnetometer-based magnetoencephalography (OPM-MEG) - to study oscillations during brain development. We show how a unique 192-channel OPM-MEG device, which is adaptable to head size and robust to participant movement, can be used to collect high-fidelity electrophysiological data in individuals aged between 2 and 34 years. Data were collected during a somatosensory task, and we measured both stimulus-induced modulation of beta oscillations in sensory cortex, and whole-brain connectivity, showing that both modulate significantly with age. Moreover, we show that pan-spectral bursts of electrophysiological activity drive task-induced beta modulation, and that their probability of occurrence and spectral content change with age. Our results offer new insights into the developmental trajectory of beta oscillations and provide clear evidence that OPM-MEG is an ideal platform for studying electrophysiology in neurodevelopment.

A Novel, Robust, and Portable Platform for Magnetoencephalography using Optically Pumped Magnetometers

Magnetoencephalography (MEG) measures brain function via assessment of magnetic fields generated by neural currents. Conventional MEG uses superconducting sensors, which place significant limitations on performance, practicality, and deployment; however, the field has been revolutionised in recent years by the introduction of optically-pumped-magnetometers (OPMs). OPMs enable measurement of the MEG signal without cryogenics, and consequently the conception of 'OPM-MEG' systems which ostensibly allow increased sensitivity and resolution, lifespan compliance, free subject movement, and lower cost. However, OPM-MEG remains in its infancy with limitations on both sensor and system design. Here, we report a new OPM-MEG design with miniaturised and integrated electronic control, a high level of portability, and improved sensor dynamic range (arguably the biggest limitation of existing instrumentation). We show that this system produces equivalent measures when compared to an established instrument; specifically, when measuring task-induced beta-band, gamma-band and evoked neuro-electrical responses, source localisations from the two systems were highly comparable and temporal correlation was >0.7 at the individual level and >0.9 for groups. Using an electromagnetic phantom, we demonstrate improved dynamic range by running the system in background fields up to 8 nT. We show that the system is effective in gathering data during free movement (including a sitting-to-standing paradigm) and that it is compatible with simultaneous electroencephalography (EEG - the clinical standard). Finally, we demonstrate portability by moving the system between two laboratories. Overall, our new system is shown to be a significant step forward for OPM-MEG technology and offers an attractive platform for next generation functional medical imaging.

Challenges in international health financing and implications for the new pandemic fund

BACKGROUND

The failures of the international COVID-19 response highlighted key gaps in pandemic preparedness and response (PPR). The G20 and WHO have called for additional funding of $10.5 billion per year to adequately strengthen the global PPR architecture. In response to these calls, in 2022 the World Bank announced the launch of a new Financial Intermediary Fund (The Pandemic Fund) to catalyse this additional funding. However, there is considerable unclarity regarding the governance makeup and financial modalities of the Pandemic Fund, and divergence of opinion about whether the Fund has been successfully designed to respond to key challenges in global health financing.

METHODS/RESULTS

The article outlines eight challenges associated with global health financing instruments and development aid for health within the global health literature. These include misaligned aid allocation; accountability; multistakeholder representation and participation; country ownership; donor coherency and fragmentation; transparency; power dynamics, and; anti-corruption. Using available information about the Pandemic Fund, the article positions the Pandemic Fund against these challenges to determine in what ways the financing instrument recognizes, addresses, partially addresses, or ignores them. The assessment argues that although the Pandemic Fund has adopted a few measures to recognise and address some of the challenges, overall, the Pandemic Fund has unclear policies in response to most of the challenges while leaving many unaddressed.

CONCLUSION

It remains unclear how the Pandemic Fund is explicitly addressing challenges widely recognized in the global health financing literature. Moreover, there is evidence that the Pandemic Fund might be exacerbating these global financing challenges, thus raising questions about its potential efficacy, suitability, and chances of success. In response, this article offers four sets of policy recommendations for how the Pandemic Fund and the PPR financing architecture might respond more effectively to the identified challenges.

Naturalistic Hyperscanning with Wearable Magnetoencephalography

The evolution of human cognitive function is reliant on complex social interactions which form the behavioural foundation of who we are. These social capacities are subject to dramatic change in disease and injury; yet their supporting neural substrates remain poorly understood. Hyperscanning employs functional neuroimaging to simultaneously assess brain activity in two individuals and offers the best means to understand the neural basis of social interaction. However, present technologies are limited, either by poor performance (low spatial/temporal precision) or an unnatural scanning environment (claustrophobic scanners, with interactions via video). Here, we describe hyperscanning using wearable magnetoencephalography (MEG) based on optically pumped magnetometers (OPMs). We demonstrate our approach by simultaneously measuring brain activity in two subjects undertaking two separate tasks-an interactive touching task and a ball game. Despite large and unpredictable subject motion, sensorimotor brain activity was delineated clearly, and the correlation of the envelope of neuronal oscillations between the two subjects was demonstrated. Our results show that unlike existing modalities, OPM-MEG combines high-fidelity data acquisition and a naturalistic setting and thus presents significant potential to investigate neural correlates of social interaction.

The Dynamics of Power Flow From the Global Health Financing Comment on "Power Dynamics Among Health Professionals in Nigeria: A Case Study of the Global Fund Policy Process"

This article agrees with Lassa et al that biomedical paradigms and medical professionals are a dominating force within the policy dynamics of the Global Fund to Fight AIDS, Tuberculosis and Malaria (GFATM) and that there needs to be greater community involvement in how global health initiatives (GHIs) are adopted, designed, implemented and evaluated. However, we argue that many of the conditions identified are entrenched and perpetuated by how GHIs are financed and the financing modalities employed in Development Aid for Health (DAH), particularly in low resource settings. As a result, the dynamics of power not only flow from traditionally entrenched epistemic authorities but are disproportionally sustained by global health financing modalities that favour particular GHIs over others. As we argue, these DAH modalities can exert forms of power with problematic effects on policy-making.

Measurement of Frontal Midline Theta Oscillations using OPM-MEG

Optically pumped magnetometers (OPMs) are an emerging lightweight and compact sensor that can measure magnetic fields generated by the human brain. OPMs enable construction of wearable magnetoencephalography (MEG) systems, which offer advantages over conventional instrumentation. However, when trying to measure signals at low frequency, higher levels of inherent sensor noise, magnetic interference and movement artefact introduce a significant challenge. Accurate characterisation of low frequency brain signals is important for neuroscientific, clinical, and paediatric MEG applications and consequently, demonstrating the viability of OPMs in this area is critical. Here, we undertake measurement of theta band (4-8 Hz) neural oscillations and contrast a newly developed 174 channel triaxial wearable OPM-MEG system with conventional (cryogenic-MEG) instrumentation. Our results show that visual steady state responses at 4 Hz, 6 Hz and 8 Hz can be recorded using OPM-MEG with a signal-to-noise ratio (SNR) that is not significantly different to conventional MEG. Moreover, we measure frontal midline theta oscillations during a 2-back working memory task, again demonstrating comparable SNR for both systems. We show that individual differences in both the amplitude and spatial signature of induced frontal-midline theta responses are maintained across systems. Finally, we show that our OPM-MEG results could not have been achieved without a triaxial sensor array, or the use of postprocessing techniques. Our results demonstrate the viability of OPMs for characterising theta oscillations and add weight to the argument that OPMs can replace cryogenic sensors as the fundamental building block of MEG systems.

Exploring direct and indirect predictors of heart disease information seeking

BACKGROUND

Based on the integrative model of behavioral prediction, we examined predictors of heart disease information seeking. We also examined demographic and individual factors associated with seeking-related perceived norms, attitudes, and perceived behavioral control.

METHODS

Non-Hispanic White and Black participants, aged 45 and older, completed a cross sectional online survey (N = 383). Stepwise logistic and multiple linear regression models were tested to assess study hypotheses, as well as tests of indirect effects.

RESULTS

Perceived norms, attitudes and perceived behavioral control were positively associated with heart disease information seeking, but when controlling for distal variables only the perceived norm-behavior association remained significant (p <.05). Indirect effects of distal variables (race, heart disease risk, perceived heart disease susceptibility and information engagement orientation) on information seeking were also detected via perceived norms.

CONCLUSIONS

Our results provide support for the integrative model as a framework for predicting information seeking, but further highlight the important role of distal predictors and perceived norms on heart disease seeking intentions. When communicating to promote heart disease information acquisition, communicators should pay particular attention to promoting information seeking as a normative behavior, particularly among those who perceive a lower risk of heart disease and who may be less engaged with health information more generally.

A 90-channel triaxial magnetoencephalography system using optically pumped magnetometers

Magnetoencephalography (MEG) measures the small magnetic fields generated by current flow in neural networks, providing a noninvasive metric of brain function. MEG is well established as a powerful neuroscientific and clinical tool. However, current instrumentation is hampered by cumbersome cryogenic field-sensing technologies. In contrast, MEG using optically pumped magnetometers (OPM-MEG) employs small, lightweight, noncryogenic sensors that provide data with higher sensitivity and spatial resolution, a natural scanning environment (including participant movement), and adaptability to any age. However, OPM-MEG is new and the optimum way to design a system is unknown. Here, we construct a novel, 90-channel triaxial OPM-MEG system and use it to map motor function during a naturalistic handwriting task. Results show that high-precision magnetic field control reduced background fields to ∼200 pT, enabling free participant movement. Our triaxial array offered twice the total measured signal and better interference rejection compared to a conventional (single-axis) design. We mapped neural oscillatory activity to the sensorimotor network, demonstrating significant differences in motor network activity and connectivity for left-handed versus right-handed handwriting. Repeatability across scans showed that we can map electrophysiological activity with an accuracy ∼4 mm. Overall, our study introduces a novel triaxial OPM-MEG design and confirms its potential for high-performance functional neuroimaging.

The role of health systems for health security: a scoping review revealing the need for improved conceptual and practical linkages

BACKGROUND

Practical links between health systems and health security are historically prevalent, but the conceptual links between these fields remain under explored, with little on health system strengthening. The need to address this gap gains relevance in light of the COVID-19 pandemic as it demonstrated a crucial relationship between health system capacities and effective health security response. Acknowledging the importance of developing stronger and more resilient health systems globally for health emergency preparedness, the WHO developed a Health Systems for Health Security framework that aims to promote a common understanding of what health systems for health security entails whilst identifying key capacities required.

METHODS/ RESULTS

To further explore and analyse the conceptual and practical links between health systems and health security within the peer reviewed literature, a rapid scoping review was carried out to provide an overview of the type, extent and quantity of research available. Studies were included if they had been peer-reviewed and were published in English (seven databases 2000 to 2020). 343 articles were identified, of those 204 discussed health systems and health security (high and medium relevance), 101 discussed just health systems and 47 discussed only health security (low relevance). Within the high and medium relevance articles, several concepts emerged, including the prioritization of health security over health systems, the tendency to treat health security as exceptionalism focusing on acute health emergencies, and a conceptualisation of security as 'state security' not 'human security' or population health.

CONCLUSION

Examples of literature exploring links between health systems and health security are provided. We also present recommendations for further research, offering several investments and/or programmes that could reliably lead to maximal gains from both a health system and a health security perspective, and why these should be explored further. This paper could help researchers and funders when deciding upon the scope, nature and design of future research in this area. Additionally, the paper legitimises the necessity of the Health Systems for Health Security framework, with the findings of this paper providing useful insights and evidentiary examples for effective implementation of the framework.

The dynamic theory of reasoned action: evidence for a reverse causal process in the context of WHO handwashing guidelines

OBJECTIVE

This study provided a first empirical test of the Reverse Dynamic Theory of Reasoned Action (RDTRA) developed by Boster et al.

DESIGN

In a longitudinal experiment, 169 participants were exposed to a WHO handwashing-guidelines behavioural induction, followed by an immediate posttest and a follow-up one week later.

MAIN OUTCOME MEASURES

The study measured attitudes and norms about WHO handwashing guidelines, as well as self-reported handwashing behaviour.

RESULTS

The experimental induction produced variance in self-reported handwashing behaviour, allowing a test of the RDTRA using path analysis and structural equation modelling (SEM). Results were consistent with the RDTRA, with a positive effect of behaviour on both the attitude and norm coupled with excellent model fit. Results were inconsistent with behaviour as an outcome of attitudes and norms in this context.

CONCLUSION

For health behaviours, such as the WHO handwashing technique, initial behavioural adoption may promote subsequent shaping of attitudes and perceived norms. Boundary conditions for this effect may include the degree of spontaneity and consent involved in behaviour adoption.

Mapping buyer's clubs; what role do they play in achieving equitable access to medicines?

Buyer's clubs were first recognised during the HIV/AIDS pandemic in the 1980s and focussed on knowledge curation and distribution of treatments. In the past decade, there has been a resurgence of buyer's clubs, mostly focussed on hepatitis C treatment and PrEP. This paper aims to increase understanding of buyer's clubs and stimulate discussion on their role in achieving equitable access to medicines. Our proposed definition of a buyer's club is 'a community-led organisation or group which seeks to improve an individual's access to medication through knowledge sharing and/or distribution as its primary goal'. The logistical and relational infrastructures of buyer's clubs have been mapped out. Networks and communities are integral to buyer's clubs by facilitating practical aspects of buyer's clubs and creating a sense of community that serves as a foundation of trust. For a user to receive necessary medical support, doctors play a crucial role, yet, obtaining this support is difficult. Whilst buyer's clubs are estimated to have enabled thousands of people to access medicines, and they run the risk of perpetuating health inequities and injustices. They may have the potential to serve as a health activism tool to stimulate sustainable changes; however, this needs to be explored further.

Investigation of factors affecting the adsorption of functional molecules onto gel silicas

Flow microcalorimetry and infrared spectroscopy were used to study the surface structure and adsorptive properties of a series of calcined and uncalcined porous silicas. The adsorbates DL-menthol, (R)-(+)-limonene, (+/-)-citronellal and carvone were selected for their functionality, that included carbonyl, vinylic and hydroxyl groups. The amounts of probe retained by the silicas together with the energy exchange involved in the adsorption/desorption process were determined by flow microcalorimetry. The functional groups involved in these interactions were studied by means of infrared spectroscopy. It was observed that the strongest interactions with the silica surface took place through hydrogen bonding onto the surface silanol. The most retentive probes were found to be those with a carbonyl group in their structure. Adsorption onto calcined silicas was found to be less energetic than onto the equivalent calcined samples. The adsorption densities were compared with theoretical predictions based on molecular models. In all cases apart from citronellal monolayer coverage were not observed due to steric effects.

The effects of the novel, reversible epidermal growth factor receptor/ErbB-2 tyrosine kinase inhibitor, GW2016, on the growth of human normal and tumor-derived cell lines in vitro and in vivo

The epidermal growth factor receptor (EGFR) and ErbB-2 transmembrane tyrosine kinases are currently being targeted by various mechanisms in the treatment of cancer. GW2016 is a potent inhibitor of the ErbB-2 and EGFR tyrosine kinase domains with IC50 values against purified EGFR and ErbB-2 of 10.2 and 9.8 nM, respectively. This report describes the efficacy in cell growth assays of GW2016 on human tumor cell lines overexpressing either EGFR or ErbB-2: HN5 (head and neck), A-431 (vulva), BT474 (breast), CaLu-3 (lung), and N87 (gastric). Normal human foreskin fibroblasts, nontumorigenic epithelial cells (HB4a), and nonoverexpressing tumor cells (MCF-7 and T47D) were tested as negative controls. After 3 days of compound exposure, average IC50 values for growth inhibition in the EGFR- and ErbB-2-overexpressing tumor cell lines were < 0.16 microM. The average selectivity for the tumor cells versus the human foreskin fibroblast cell line was 100-fold. Inhibition of EGFR and ErbB-2 receptor autophosphorylation and phosphorylation of the downstream modulator, AKT, was verified by Western blot analysis in the BT474 and HN5 cell lines. As a measure of cytotoxicity versus growth arrest, the HN5 and BT474 cells were assessed in an outgrowth assay after a transient exposure to GW2016. The cells were treated for 3 days in five concentrations of GW2016, and cell growth was monitored for an additional 12 days after removal of the compound. In each of these tumor cell lines, concentrations of GW2016 were reached where outgrowth did not occur. Furthermore, growth arrest and cell death were observed in parallel experiments, as determined by bromodeoxyuridine incorporation and propidium iodide staining. GW2016 treatment inhibited tumor xenograft growth of the HN5 and BT474 cells in a dose-responsive manner at 30 and 100 mg/kg orally, twice daily, with complete inhibition of tumor growth at the higher dose. Together, these results indicate that GW2016 achieves excellent potency on tumor cells with selectivity for tumor versus normal cells and suggest that GW2016 has value as a therapy for patients with tumors overexpressing either EGFR or ErbB-2.

Expression and purification of active recombinant ATM protein from transiently transfected mammalian cells

The gene mutated in the human disease ataxia telangiectasia (AT), termed ATM, encodes a large protein kinase involved in DNA repair and cell cycle control. Biochemical characterization of ATM function has been somewhat difficult because of its large size (approximately 370 kDa) and relatively low level of expression in several systems. The majority of studies have used immunoprecipitated ATM or purified ATM obtained through relatively complex procedures. Here, we describe an efficient method for the expression and purification of FLAG-epitope-tagged recombinant human ATM protein (F-ATM). This method utilizes the expression of F-ATM in transiently transfected 293T cells followed by anti-FLAG-agarose affinity chromatography. The transfection procedure has been optimized for large (225-cm(2)) culture flasks and F-ATM can be purified to near homogeneity as judged by SDS-PAGE. This procedure yields approximately 1 microg of catalytically active F-ATM protein/225-cm(2) flask that can be used for biochemical studies.

Monoclonal antibodies generated against recombinant ATM support kinase activity

We report on the rapid generation of two monoclonal antibodies, ATM A16.35 and ATM D16.11, that bind to the kinase domain of mutated ataxia telangiectasia (ATM). These antibodies were generated against E. coli-expressed recombinant protein using the RIMMS strategy. We show that ATM A16.35 binds ATM by Western blot analysis, and ATM D16.11 forms immune complexes with native ATM in immunoprecipitations without neutralizing kinase activity.

Defective potassium currents in ataxia telangiectasia fibroblasts

Similarities exist between the progressive cerebellar ataxia in ataxia telangiectasia (AT) patients and a number of neurodegenerative diseases in both mouse and man involving specific mutations in ion channels and/or ion channel activity. These relationships led us to investigate the possibility of defective ion channel activity in AT cells. We examined changes in the membrane potential of AT fibroblasts in response to extracellular cation addition and found that the ability of AT fibroblasts to depolarize in response to increasing concentrations of extracellular K+ is significantly reduced when compared with control fibroblasts. Electrophysiological measurements performed with a number of AT cell lines, as well as two matched sets of primary AT fibroblast cultures, reveal that outward rectifier K+ currents are largely absent in AT fibroblasts in comparison with control cells. These K+ current defects can be corrected in AT fibroblasts transfected with the full-length ATM cDNA. These data implicate, for the first time, a role for ATM in the regulation of K+ channel activity and membrane potential.

Serum starved v-mos-transformed cells are unable to appropriately downregulate cyclins and CDKs

Serum deprived v-mos-transformed NIH3T3 cells are unable to enter a true quiescent state, but instead, arrest in the early G1 phase of the cell cycle. We have analysed several cell cycle regulatory proteins in these G1 arrested cells and show altered regulation in the expression and activity of certain cyclins and cyclin-dependent kinases. In particular, p34cdc2, cyclin A, cyclin D and cyclin E are not appropriately down-regulated in serum starved, G1 arrested, v-mos-transformed cells as compared with quiescent NIH3T3 cells. Furthermore, serum starved v-mos-transformed cells have elevated histone H1 kinase activity associated with cyclin A, cyclin E, p33cdk2, and p34cdc2. Using a metallothionein-inducible c-mos(mu) expression system, we show that c-mos(mu) induction in quiescent NIH3T3 cells causes elevated expression of p34cdc2. However, this induction of c-mos(mu) and subsequent expression of p34cdc2 was not sufficient to promote significant entry of cells into S phase. Analysis of extracts from serum starved v-H-ras, v-src, and tpr-met transformed NIH3T3 cells demonstrates that these oncogene-transformed cells also contain elevated levels of p34cdc2. We propose that the altered regulation of these critical cell cycle regulatory molecules, and specifically the inability to fully downregulate their activity, contributes significantly to neoplastic transformation and subsequent unregulated growth of tumor cells.

Deregulation of specific E2F complexes by the v-mos oncogene

The product of the c-mos proto-oncogene is a protein kinase that is normally expressed in germ cells and functions during oocyte maturation. It has been shown, however, that inappropriate expression of either the viral or cellular mos gene can induce neoplastic progression in somatic cells. Furthermore, v-mos-transformed NIH3T3 cells will undergo arrest of proliferation in early G1 upon serum withdrawal but are unable to appropriately down-regulate cell cycle regulatory proteins, such as cyclin and cdc2 proteins, that normally are down-regulated in quiescent, untransformed NIH3T3 cells. Since the levels of these proteins are partially transcriptionally controlled, we investigated whether there were alterations in the expression of E2F and AP-1 transcription factor complexes. Indeed, the putative G0/G1-specific p130-E2F complex that is normally observed during low serum-induced cell cycle arrest in NIH3T3 cells is not present in serum starved v-mos-transformed cells. Instead, G1-phase arrested v-mos-transformed cells stably express two E2F protein complexes that are normally observed only during S-phase in untransformed cells. The elevation of these complexes in arrested v-mos-transformed cells may be the cause of the transcriptional activation of the E2F-regulated genes cdc2, DHFR, cyclin A, and E2F1 seen in serum starved v-mos-transformed cells. In addition, there are high levels of AP-1 DNA binding activity in serum starved v-mos-transformed cells compared to very low amounts in nontransformed cells. This altered regulation of transcription factor complexes and cell cycle control proteins upon serum withdrawal may provide a mechanism for the uncontrolled cell growth associated with neoplastic transformation induced by certain proto-oncogenes.

Subject matter and poetic devices in psychotics' poetry

It has long been supposed that there is a connection between the mental processes of psychosis and those of creativity. The present study aimed to investigate this idea by means of a comparison between the poetic output of psychotics and that of normals, taking as its starting-point the notion that if there are observable differences between these two groups in terms of subject matter and linguistic features, this would suggest that creativity and psychosis are not to be identified with each other. Eighty poems by contemporary, non-professional poets (40 by psychotics and 40 by normals) were analysed on 11 different dimensions. The two samples of poems were highly similar on most of the dimensions investigated. The main differences found were in the incidence of self-analysis as a theme, reference to proper names and specific locations, and in the proportion of metaphors which fell into the category 'psychological/physical'. The two latter differences appeared to be largely a product of the first. It was concluded that although 'normal' and 'psychotic' poetic activities are not identical, they are closely related. This may be either because general poetic creativity does have psychotic features, or because the poetic function of language was relatively spared in at least this sample of psychotics.

A link between catalytic activity, IgE-independent mast cell activation, and allergenicity of bee venom phospholipase A2

The molecular and cellular mechanisms controlling Ab isotype selection following encounter of a given Ag are still unclear, although the regulatory role of cytokines is established. In the present study we explored the possibility that the nonimmunologic interaction of an allergen with cells of the innate immune system might result in a release of mediators that promote IgE isotype selection in adaptive responses. Using the bee venom allergen phospholipase A2 (PLA2) and a mutant variant lacking enzymatic function, we show that PLA2, but not its catalytically inactive variant, is able to induce IgE-independent mediator release, including IL-4, from rodent mast cells. Assessing the in vivo relevance of these observations, we find that repeated injections of low doses of active enzyme into mice induce the synthesis of high levels of PLA2-specific IgE, while immunization with the inactive form yields no detectable IgE response. Both Ags were similarly immunogenic when high doses of Ag were used for immunization. These findings suggest that mast cells might be a source of IL-4 at the onset of specific immunity against sources of allergens such as bee venom that contain PLA2 and support the concept that the biologic action of an Ag on cells of the innate immune system can play a role in determining adaptive immune responses.

A link between catalytic activity, IgE-independent mast cell activation, and allergenicity of bee venom phospholipase A2

The molecular and cellular mechanisms controlling Ab isotype selection following encounter of a given Ag are still unclear, although the regulatory role of cytokines is established. In the present study we explored the possibility that the nonimmunologic interaction of an allergen with cells of the innate immune system might result in a release of mediators that promote IgE isotype selection in adaptive responses. Using the bee venom allergen phospholipase A2 (PLA2) and a mutant variant lacking enzymatic function, we show that PLA2, but not its catalytically inactive variant, is able to induce IgE-independent mediator release, including IL-4, from rodent mast cells. Assessing the in vivo relevance of these observations, we find that repeated injections of low doses of active enzyme into mice induce the synthesis of high levels of PLA2-specific IgE, while immunization with the inactive form yields no detectable IgE response. Both Ags were similarly immunogenic when high doses of Ag were used for immunization. These findings suggest that mast cells might be a source of IL-4 at the onset of specific immunity against sources of allergens such as bee venom that contain PLA2 and support the concept that the biologic action of an Ag on cells of the innate immune system can play a role in determining adaptive immune responses.

Molecular mechanisms of environmental carcinogenesis

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Defective G2 checkpoint function in cells from individuals with familial cancer syndromes

The early events in the G2 checkpoint response to ionizing radiation (IR) were analyzed in diploid normal human fibroblasts (NHFs) and fibroblasts from patients with two heritable cancer syndromes. Exposure to gamma-radiation of asynchronously growing NHFs resulted in a rapid reduction in the number of cells in mitosis (G2 delay) and was accompanied by a quantitatively similar reduction in the p34CDC2/cyclin B in vitro histone H1 kinase activity as compared with sham-treated controls. This G2 delay was strong by 1 h following exposure to IR, maximal by 2 h, and was accompanied by an accumulation of tyrosine-phosphorylated p34CDC2 molecules. In contrast, fibroblasts from individuals with ataxia telangiectasia displayed significantly less reduction of the mitotic index or histone H1 kinase activity after IR. Low passage fibroblasts from individuals with Li-Fraumeni syndrome having one wild-type and one mutated p53 allele were similar to NHFs in their immediate G2 checkpoint response to IR, as were NHFs expressing the human papilloma virus type 16 E6 gene product (functionally inactivating p53) and low passage cells from p53-deficient mouse embryos. However, the p53-deficient fibroblasts were genomically unstable and became defective in their early G2 checkpoint response to IR. Furthermore, immortal Li-Fraumeni syndrome fibroblasts lacking wild-type p53 displayed an attenuated G2 checkpoint response. These results link the early events in G2 checkpoint response to IR in NHFs with a rapid inhibition of p34CDC2/cyclin B protein kinase activity and demonstrate that while not required for this immediate G2 delay, lack of p53 can lead to subsequent genetic alterations that result in defective G2 checkpoint function.

Labor experiences of childhood sexual abuse survivors

This field study used the ethnographic method to describe and analyze the labor experiences of childhood sexual abuse survivors. The sample included seven sexual abuse survivors, five nurse-midwives, and three labor and delivery nurses. Data collection included in-depth interviews, participant observation in labor and delivery over a period of six years, and anecdotal material from the literature. Analysis followed Spradley's Developmental Research Sequence and included domain, taxonomic, componential and theme analysis. Women reported both forgetting and remembering abusive incidents, and described labor sensations reminiscent of sexual abuse. A heuristic for appraising labor styles suggestive of past sexual abuse includes fighting, taking control, surrendering, and retreating. These styles are considered extremes of women's reactions to labor and are directly linked to posttraumatic stress disorder. This study demonstrated that it is important for perinatal caregivers to understand the link between childhood sexual abuse and childbirth so that they can assist women to have a positive birth experience.

v-mos-transformed cells fail to enter quiescence but growth arrest in G1 following serum withdrawal

The product of the mos protooncogene normally functions in the induction of meiosis and regulation of cell-cycle progression in oocytes. Here we have investigated the cell-cycle progression of NIH3T3 cells transformed by the v-mos gene. Flow cytometric analysis showed that logarithmically growing v-mos-transformed cells do not differ from their nontransformed counterparts in the distribution of cells in the G1, S, and G2/M phases. Likewise, after serum withdrawal for 48 h, both normal and v-mos-transformed NIH3T3 cells have essentially ceased proliferation, as analyzed by flow cytometry, [3H]thymidine and BrdU incorporation into newly synthesized DNA, and mitotic indexes. However, while the normal NIH3T3 cells are arrested in a quiescent state, the v-mos-transformed cells are arrested in early to mid G1, prior to the point where cells require certain amino acids for proliferation (V point). In agreement with these different arrest points, the v-mos-transformed cells enter S phase following serum stimulation within about 8 h, without the additional 4- to 6-h lag period characteristically displayed by the parental NIH3T3 cells. In addition, we show a lack of expression of a growth arrest-specific gene product, gas1, in the serum-arrested v-mos-transformed cells. These data demonstrated that v-mos-transformed cells display growth characteristics that differ fundamentally from those of normal cells or cells transformed by overexpression of myc [1]. Our results suggest that the v-mos oncoprotein transforms cells, at least in part, by preventing exit from the cell cycle into quiescence.

Constitutive mutants of the protein kinase STE11 activate the yeast pheromone response pathway in the absence of the G protein

STE4 encodes the beta-subunit of a heterotrimeric guanine nucleotide-binding protein (G protein) that is an early and essential component of the pheromone signal transduction pathway. From a ste4 deletion strain we have isolated both dominant and recessive suppressors that show increased transcription of pheromone responsive genes and have regained the ability to mate, albeit at a low level. Each of these suppressor mutations suppresses ste4 and ste5 deletions but not deletions in STE7, STE11, or STE12. Among the dominant mutations, we have identified two alleles of STE11, a gene that encodes a protein kinase activity essential for mating. One allele contains an alteration in the putative regulatory domain of the protein kinase; the second allele has an alteration in the catalytic site. In strains carrying these mutations, a second protein kinase required for mating, STE7, becomes hyperphosphorylated, just as it does in wild-type cells treated with pheromone. Thus, a protein kinase cascade appears to be an essential feature of the response pathway and probably connects the receptor/G protein to an identified transcription factor, STE12.

STE11 is a protein kinase required for cell-type-specific transcription and signal transduction in yeast

The STE11 gene of Saccharomyces cerevisiae is one of several genes required for mating between two haploid cell types of this yeast. Its product is required for response to a signal that causes arrest of the mitotic cell cycle in the G1 phase and induction of mating-type-specific genes. The nucleotide sequence of the STE11 gene was determined. The predicted amino acid sequence shows homology to the protein kinase family. We demonstrate that the STE11 product has kinase catalytic activity and that this activity is required for its in vivo functions.

Relationship of cranial ultrasonography, visual and auditory evoked responses with neurodevelopmental outcome

Sixty-two preterm infants were followed up with flash visual evoked responses (VERs), brainstem auditory evoked responses (BAERs) and neurodevelopmental assessments for 18 months after term. Cranial ultrasonography showed that 18 infants developed intraventricular haemorrhage (IVH) during the newborn period and four of six infants with grade III or IV haemorrhage had absent VERs at term. The mean latency of the VER in the infants with IVH was significantly shorter than that of infants without IVH. There was no correlation between the degree of ventricular dilatation at term and the latency of the VER. Six months after term the four infants with previously absent VERs had normal responses, though there was still a significant difference between the latencies of infants with and without IVH. At 12 and 18 months of age these differences had disappeared. BAERs were not significantly different in the infants with and without IVH, and there was no difference in the VERs or BAERs of infants with neurodevelopmental delay and those developing normally. Neither flash VERs nor BAERs provide a good prognostic indicator of future neurodevelopmental disability or outcome.

A yeast-Escherichia coli shuttle vector containing the M13 origin of replication

A yeast-Escherichia coli shuttle vector containing the M13 origin of replication has been constructed. This vector allows selection and replication in both Saccharomyces cerevisiae and E. coli, as well as single-stranded packaging from E. coli upon infection with a helper phage. The presence of a polylinker with various unique restriction sites facilitates the cloning of desired genes.

Exponential model for a regulatory enzyme. Computer program for the determination of the model constants from initial velocity data

The paper describes a program (DESCENT) which evaluates the constants of the exponential model for a regulatory enzyme with up to four substrates or up to three substrates and one effector. The program operates by repetitive adjustment of the model constants so as to secure a better fit between the observed and calculated initial velocities of reaction. At each adjustment, all the constants are incremented simultaneously by amounts determined by a steepest descent criterion. The program is tested by artificial data with and without added error and it is shown that good estimates of the constants can be recovered.

Calculation of Hill slopes predicted by the four ligand exponential model for a regulatory enzyme

The Hill slopes predicted by the exponential model for a regulatory enzyme have been calculated by two separate methods, one analytical and the other numerical. Both methods are applicable to enzymes with up to 4 substrates; alternatively, one substrate may be replaced by an effector. The maximum or minimum Hill slope can also be ascertained by an extension of the analytical method.

The regulatory properties of yeast pyruvate kinase. Effects of NH4+ and K+ concentrations

The kinetics of pyruvate kinase from Saccharomyces cerevisiae were studied at 25 degrees C and pH 6.2 as a function of the concentrations of ADP, phosphoenolpyruvate, Mg2+ and either NH4+ or K+. The data were analysed by the exponential model for four substrates, obtained by extension of the model described by Ainsworth, Kinderlerer & Gregory [(1983) Biochem. J. 209, 401-411]. On that basis, it was concluded that NH4+ binding is almost non-interactive but leads to the appearance of positive interaction in the velocity response to increase in its concentration because of positive interactions with phosphoenolpyruvate and Mg2+. The data obtained with K+ lead to the same conclusions and differ only in suggesting that NH4+ is bound more strongly to the enzyme than is K+. Both data sets are used as the basis for a discussion of the substrate interactions of pyruvate kinase and it appears therefrom that the heterotropic interactions accord with what is known of the events that take place at the active site during catalysis. The paper also reports a determination of the dissociation constants for the NH4+ complexes with ADP and phosphoenolpyruvate and an examination of the simultaneous activation of pyruvate kinase by K+ and NH4+ ions.

The regulatory properties of yeast pyruvate kinase. Effect of pH

The kinetics of pyruvate kinase from Saccharomyces cerevisiae were studied at 25 degrees C as a function of the concentrations of the substrates ADP, phosphoenolpyruvate and Mg2+ and the effector H+ in the pH range 5-6.6. The enzyme was activated by 100 mM-K+ and 32 mM-NH4+ throughout. It was found that the data could be described by the exponential model for a regulatory enzyme. On that basis, it was concluded that the binding of H+ is positively interactive and that the protonated enzyme is catalytically inactive. It was also found that H+ interacts positively with phosphoenolpyruvate but negatively with both ADP and Mg2+.