Achievement of Target Gain Larger than Unity in an Inertial Fusion Experiment

On December 5, 2022, an indirect drive fusion implosion on the National Ignition Facility (NIF) achieved a target gain G_{target} of 1.5. This is the first laboratory demonstration of exceeding "scientific breakeven" (or G_{target}>1) where 2.05 MJ of 351 nm laser light produced 3.1 MJ of total fusion yield, a result which significantly exceeds the Lawson criterion for fusion ignition as reported in a previous NIF implosion [H. Abu-Shawareb et al. (Indirect Drive ICF Collaboration), Phys. Rev. Lett. 129, 075001 (2022)PRLTAO0031-900710.1103/PhysRevLett.129.075001]. This achievement is the culmination of more than five decades of research and gives proof that laboratory fusion, based on fundamental physics principles, is possible. This Letter reports on the target, laser, design, and experimental advancements that led to this result.

1336 TOWARDS AN UNDERSTANDING OF THE BIOLOGICAL MECHANISMS OF DELIRIUM USING FUNCTIONAL MRI: PILOT STUDY

Introduction

Delirium is a common condition in older hospitalised patients causing high morbidity and mortality. The neurobiological basis for delirium is uncertain and, for numerous reasons, research in this area has been limited. Several recent studies have demonstrated that functional neuroimaging in delirium is achievable and has suggested that a brain region termed the default mode network (DMN), may play a cardinal role in delirium pathogenesis. We set out to develop a pilot study to demonstrate that it is feasible to undertake functional magnetic resonance imaging (fMRI) scans in older patients with acute delirium.

Methods

Observational pilot study obtaining a fMRI scan of inpatients in an Australian, tertiary hospital, geriatric ward. Eligible patients diagnosed as delirious by a geriatrician were compared against non-delirious controls. Informed consent was obtained. A novel scanning paradigm was developed. Sequences assed brain structure and functional networks in resting state and during a simple task of sustained attention and response inhibition.

Results

11 participants have been scanned. 6 participants were delirious: mean age 81 years (range 77 – 85 years), 3 female. 5 participants were non-delirious: mean age 83.4years (range 79 -90 years), 2 female. 10 of the 11 participants completed the full imaging protocol, including task engagement. Head movement during scanning, was generally within acceptable limits. Data demonstrates considerable cortical atrophy and ventricular enlargement consistent with age. Preliminary fMRI analyses show a variable pattern of cortical recruitment during task engagement in delirious patients.

Conclusions

These findings show it is ethically and logistically feasible to engage elderly patients with acute delirium into a high end structural and functional imaging study.

Lawson Criterion for Ignition Exceeded in an Inertial Fusion Experiment

For more than half a century, researchers around the world have been engaged in attempts to achieve fusion ignition as a proof of principle of various fusion concepts. Following the Lawson criterion, an ignited plasma is one where the fusion heating power is high enough to overcome all the physical processes that cool the fusion plasma, creating a positive thermodynamic feedback loop with rapidly increasing temperature. In inertially confined fusion, ignition is a state where the fusion plasma can begin "burn propagation" into surrounding cold fuel, enabling the possibility of high energy gain. While "scientific breakeven" (i.e., unity target gain) has not yet been achieved (here target gain is 0.72, 1.37 MJ of fusion for 1.92 MJ of laser energy), this Letter reports the first controlled fusion experiment, using laser indirect drive, on the National Ignition Facility to produce capsule gain (here 5.8) and reach ignition by nine different formulations of the Lawson criterion.

Melanoma secretion of transforming growth factor-β2 leads to loss of epidermal AMBRA1 threatening epidermal integrity and facilitating tumour ulceration

BACKGROUND

For patients with early American Joint Committee on Cancer (AJCC)-stage melanoma the combined loss of the autophagy regulatory protein AMBRA1 and the terminal differentiation marker loricrin in the peritumoral epidermis is associated with a significantly increased risk of metastasis.

OBJECTIVES

The aim of the present study was to evaluate the potential contribution of melanoma paracrine transforming growth factor (TGF)-β signalling to the loss of AMBRA1 in the epidermis overlying the primary tumour and disruption of epidermal integrity.

METHODS

Immunohistochemistry was used to analyse AMBRA1 and TGF-β2 in a cohort of 109 AJCC all-stage melanomas, and TGF-β2 and claudin-1 in a cohort of 30 or 42 AJCC stage I melanomas, respectively, with known AMBRA1 and loricrin (AMLo) expression. Evidence of pre-ulceration was analysed in a cohort of 42 melanomas, with TGF-β2 signalling evaluated in primary keratinocytes.

RESULTS

Increased tumoral TGF-β2 was significantly associated with loss of peritumoral AMBRA1 (P < 0·05), ulceration (P < 0·001), AMLo high-risk status (P < 0·05) and metastasis (P < 0·01). TGF-β2 treatment of keratinocytes resulted in downregulation of AMBRA1, loricrin and claudin-1, while knockdown of AMBRA1 was associated with decreased expression of claudin-1 and increased proliferation of keratinocytes (P < 0·05). Importantly, we show loss of AMBRA1 in the peritumoral epidermis was associated with decreased claudin-1 expression (P < 0·05), parakeratosis (P < 0·01) and cleft formation in the dermoepidermal junction (P < 0·05).

CONCLUSIONS

Collectively, these data suggest a paracrine mechanism whereby TGF-β2 causes loss of AMBRA1 overlying high-risk AJCC early-stage melanomas and reduced epidermal integrity, thereby facilitating erosion of the epidermis and tumour ulceration.

Systematic Evaluation of Kinetics and Distribution of Muscle and Lymph Node Activation Measured by 18F-FDG- and 11C-PBR28-PET/CT Imaging, and Whole Blood and Muscle Transcriptomics After Immunization of Healthy Humans With Adjuvanted and Unadjuvanted Vaccines

Systems vaccinology has been applied to detect signatures of human vaccine induced immunity but its ability, together with high definition in vivo clinical imaging is not established to predict vaccine reactogenicity. Within two European Commission funded high impact programs, BIOVACSAFE and ADITEC, we applied high resolution positron emission tomography/computed tomography (PET/CT) scanning using tissue-specific and non-specific radioligands together with transcriptomic analysis of muscle biopsies in a clinical model systematically and prospectively comparing vaccine-induced immune/inflammatory responses. 109 male participants received a single immunization with licensed preparations of either AS04-adjuvanted hepatitis B virus vaccine (AHBVV); MF59C-adjuvanted (ATIV) or unadjuvanted seasonal trivalent influenza vaccine (STIV); or alum-OMV-meningococcal B protein vaccine (4CMenB), followed by a PET/CT scan (n = 54) or an injection site muscle biopsy (n = 45). Characteristic kinetics was observed with a localized intramuscular focus associated with increased tissue glycolysis at the site of immunization detected by ¹⁸F-fluorodeoxyglucose (FDG) PET/CT, peaking after 1–3 days and strongest and most prolonged after 4CMenB, which correlated with clinical experience. Draining lymph node activation peaked between days 3–5 and was most prominent after ATIV. Well defined uptake of the immune cell-binding radioligand ¹¹C-PBR28 was observed in muscle lesions and draining lymph nodes. Kinetics of muscle gene expression module upregulation reflected those seen previously in preclinical models with a very early (~6hrs) upregulation of monocyte-, TLR- and cytokine/chemokine-associated modules after AHBVV, in contrast to a response on day 3 after ATIV, which was bracketed by whole blood responses on day 1 as antigen presenting, inflammatory and innate immune cells trafficked to the site of immunization, and on day 5 associated with activated CD4+ T cells. These observations confirm the use of PET/CT, including potentially tissue-, cell-, or cytokine/chemokine-specific radioligands, is a safe and ethical quantitative technique to compare candidate vaccine formulations and could be safely combined with biopsy to guide efficient collection of samples for integrated whole blood and tissue systems vaccinology in small-scale but intensive human clinical models of immunization and to accelerate clinical development and optimisation of vaccine candidates, adjuvants, and formulations.

Ultrasonic preparation, stability and thermal conductivity of a capped copper-methanol nanofluid

This paper describes a two-step method to prepare novel copper-methanol nanofluids capped with a short chain molecule, (3-Aminopropyl)trimethoxysilane (APTMS). Two commercial nanopowders were dispersed at various powers using a 20 kHz ultrasonic probe into solutions of methanol and the capping agent. Ultrasonic energy input was measured by calorimetry with z-average diameters, intensity and number size distributions recorded by a dynamic light scattering technique. The stability of the dispersion was monitored visually, and quantified by recording the zeta potential. Dispersions of the bare powder were used as a control. Absorption spectroscopy was used to confirm the presence of the capping agent. The thermal conductivities of 0 to 10% wt./vol. (1.1% vol.) dispersions of the capped copper-methanol nanofluid were determined using a C-Therm analyzer. Optimum ultrasonic de-agglomeration conditions gave dispersions with a z-average particle size of <200 nm and a PdI of <0.2. The capped particles showed good stability; up to six months in some instances, and an average zeta potential of +38 mV was recorded. The thermal conductivity of the nanofluid increased with concentration, and an enhancement of 9% over the base fluid was found at 10% wt./vol. (1.1% vol.). This innovative work has demonstrated the ultrasonic preparation and stability of copper nanoparticles protected with APTMS; a short chain molecule which binds to copper and prevents oxidation. The protected particles can enhance the thermal conductivity of methanol with no interference from the capping ligand.

Epidermal autophagy and beclin 1 regulator 1 and loricrin: a paradigm shift in the prognostication and stratification of the American Joint Committee on Cancer stage I melanomas

BACKGROUND

The updated American Joint Committee on Cancer (AJCC) staging criteria for melanoma remain unable to identify high-risk stage I tumour subsets.

OBJECTIVES

To determine the utility of epidermal autophagy and beclin 1 regulator 1 (AMBRA1)/loricrin (AMLo) expression as a prognostic biomarker for AJCC stage I cutaneous melanoma.

METHODS

Peritumoral AMBRA1 expression was evaluated in a retrospective discovery cohort of 76 AJCC stage I melanomas. AMLo expression was correlated with clinical outcomes up to 12 years in two independent powered, retrospective validation and qualification cohorts comprising 379 AJCC stage I melanomas.

RESULTS

Decreased AMBRA1 expression in the epidermis overlying primary melanomas in a discovery cohort of 76 AJCC stage I tumours was associated with a 7-year disease-free survival (DFS) rate of 81·5% vs. 100% survival with maintained AMBRA1 (P < 0·081). Following an immunohistochemistry protocol for semi-quantitative analysis of AMLo, analysis was undertaken in validation (n = 218) and qualification cohorts (n = 161) of AJCC stage I melanomas. Combined cohort analysis revealed a DFS rate of 98·3% in the AMLo low-risk group (n = 239) vs. 85·4% in the AMLo high-risk cohort (n = 140; P < 0·001). Subcohort multivariate analysis revealed that an AMLo hazard ratio (HR) of 4·04 [95% confidence interval (CI) 1·69-9·66; P = 0·002] is a stronger predictor of DFS than Breslow depth (HR 2·97, 95% CI 0·93-9·56; P = 0·068) in stage IB patients.

CONCLUSIONS

Loss of AMLo expression in the epidermis overlying primary AJCC stage I melanomas identifies high-risk tumour subsets independently of Breslow depth. What's already known about this topic? There is an unmet clinical need for biomarkers of early-stage melanoma. Autophagy and beclin 1 regulator 1 (AMBRA1) is a proautophagy regulatory protein with known roles in cell proliferation and differentiation, and is a known tumour suppressor. Loricrin is a marker of epidermal terminal differentiation. What does this study add? AMBRA1 has a functional role in keratinocyte/epidermal proliferation and differentiation. The combined decrease/loss of peritumoral AMBRA1 and loricrin is associated with a significantly increased risk of metastatic spread in American Joint Committee on Cancer (AJCC) stage I tumours vs. melanomas, in which peritumoral AMBRA1 and loricrin are maintained, independently of Breslow depth. What is the translational message? The integration of peritumoral epidermal AMBRA1/loricrin biomarker expression into melanoma care guidelines will facilitate more accurate, personalized risk stratification for patients with AJCC stage I melanomas, thereby facilitating stratification for appropriate follow-up and informing postdiagnostic investigations, including sentinel lymph node biopsy, ultimately resulting in improved disease outcomes and rationalization of healthcare costs.

A Comparative Phase I Study of Combination, Homologous Subtype-C DNA, MVA, and Env gp140 Protein/Adjuvant HIV Vaccines in Two Immunization Regimes

There remains an urgent need for a prophylactic HIV vaccine. We compared combined MVA and adjuvanted gp140 to sequential MVA/gp140 after DNA priming. We expected Env-specific CD4+ T-cells after DNA and MVA priming, and Env-binding antibodies in 100% individuals after boosting with gp140 and that combined vaccines would not compromise safety and might augment immunogenicity. Forty volunteers were primed three times with DNA plasmids encoding (CN54) env and (ZM96) gag-pol-nef at 0, 4 and 8 weeks then boosted with MVA-C (CN54 env and gag-pol-nef) and glucopyranosyl lipid adjuvant—aqueous formulation (GLA-AF) adjuvanted CN54gp140. They were randomised to receive them in combination at the same visit at 16 and 20 weeks (accelerated) or sequentially with MVA-C at 16, 20, and GLA-AF/gp140 at 24 and 28 weeks (standard). All vaccinations were intramuscular. Primary outcomes included ≥grade 3 safety events and the titer of CN54gp140-specific binding IgG. Other outcomes included neutralization, binding antibody specificity and T-cell responses. Two participants experienced asymptomatic ≥grade 3 transaminitis leading to discontinuation of vaccinations, and three had grade 3 solicited local or systemic reactions. A total of 100% made anti-CN54gp140 IgG and combining vaccines did not significantly alter the response; geometric mean titer 6424 (accelerated) and 6578 (standard); neutralization of MW965.2 Tier 1 pseudovirus was superior in the standard group (82 versus 45% responders, p = 0.04). T-cell ELISpot responses were CD4+ and Env-dominant; 85 and 82% responding in the accelerated and standard groups, respectively. Vaccine-induced IgG responses targeted multiple regions within gp120 with the V3 region most immunodominant and no differences between groups detected. Combining MVA and gp140 vaccines did not result in increased adverse events and did not significantly impact upon the titer of Env-specific binding antibodies, which were seen in 100% individuals. The approach did however affect other immune responses; neutralizing antibody responses, seen only to Tier 1 pseudoviruses, were poorer when the vaccines were combined and while T-cell responses were seen in >80% individuals in both groups and similarly CD4 and Env dominant, their breadth/polyfunctionality tended to be lower when the vaccines were combined, suggesting attenuation of immunogenicity and cautioning against this accelerated regimen.

Prevalence of pelvic floor symptoms in female patients attending the two-week wait clinic with suspected colorectal cancer

Introduction The aim of this study was to establish the prevalence of pelvic floor symptoms in women referred to a colorectal two-week wait (2WW) clinic with suspected colorectal cancer. Methods A questionnaire assessing faecal incontinence (FI) (Wexner score) and obstructed defecation syndrome (ODS) (Renzi score) was offered to 98 consecutive female patients attending a colorectal 2WW clinic at a single trust. Results Overall, 56 (57%) of the 98 patients had significant ODS and/or FI (scores >9/20), 33 (34%) had ODS and 40 (41%) had FI. Seventeen patients (17%) had both ODS and FI. Analysis of the 63 patients referred with a change in bowel habit (CIBH) showed 40 (63%) to be Renzi and/or Wexner positive compared with 16 (46%) of the 35 patients who presented without CIBH (p=0.095, Fisher's exact test). Further analysis showed that 31 (78%) of the 40 patients with FI presented with CIBH compared with 32 (55%) of the 58 without FI (p=0.032). In terms of ODS, 23 (70%) of the 33 patients with ODS presented with CIBH compared with 40 (62%) of the 65 without ODS (p=0.506). Conclusions Over half of the female patients attending our colorectal 2WW clinic had significant pelvic floor dysfunction (FI/ODS), which may account for their symptoms (especially in the CIBH referral category). While it is important for malignancy to be excluded, many patients may benefit from investigation and management of their pelvic floor dysfunction as the cause for their presenting symptoms.

Morning vs evening dosing of the cathepsin K inhibitor ONO-5334: effects on bone resorption in postmenopausal women in a randomized, phase 1 trial

The cathepsin K inhibitor, ONO-5334, improves bone mineral density in postmenopausal women with osteoporosis. The effects of morning versus evening administration of ONO-5334 were investigated by measuring bone turnover marker levels in healthy postmenopausal women. Morning administration of ONO-5334 showed a more consistent suppressive effect on bone resorption than evening administration.

INTRODUCTION

Bone turnover is thought to be subject to circadian variation, and the efficacy of osteoporosis treatments may be optimized by regulating the time of dosing. This study assessed whether evening administration of the cathepsin K inhibitor, ONO-5334, had a differential effect on the bone turnover marker, C-terminal telopeptide of type I collagen (CTX-I), compared with morning administration.

METHODS

This was a single-center, single blind crossover study. Fourteen healthy postmenopausal women were assigned to receive ONO-5334 150 mg once daily for 5 days in each period; they were randomized to receive either evening doses in the first period and morning doses in the second or vice versa. Serum and urinary levels of CTX-I were measured throughout the study.

RESULTS

Both regimens showed similar patterns of reduction in serum and urinary CTX-I; however, CTX-I suppression was more consistently >60% over 24 h following morning administration. Morning administration led to 6% greater suppression of 24-h serum CTX-I area under the effect curve (AUE; 69 vs 63%; P < .05) and 7% greater suppression of urinary CTX-I/creatinine AUE (93 vs 86%; P < .01) than evening administration. Higher plasma ONO-5334 concentrations were observed between 12 and 24 h postdose following morning administration, with mean trough concentrations for the morning and evening regimens at 9.4 and 4.0 ng/mL, respectively. There were no safety findings of concern.

CONCLUSION

Morning dosing of ONO-5334 is more efficacious at reducing markers of bone turnover in healthy postmenopausal women than evening dosing.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT01384188 , registered on June 27, 2011 EudraCT: 2008-006284-37.

First observations of nonhydrodynamic mix at the fuel-shell interface in shock-driven inertial confinement implosions

A strong nonhydrodynamic mechanism generating atomic fuel-shell mix has been observed in strongly shocked inertial confinement fusion implosions of thin deuterated-plastic shells filled with 3He gas. These implosions were found to produce D3He-proton shock yields comparable to implosions of identical shells filled with a hydroequivalent 50∶50 D3He gas mixture. Standard hydrodynamic mixing cannot explain this observation, as hydrodynamic modeling including mix predicts a yield an order of magnitude lower than was observed. Instead, these results can be attributed to ion diffusive mix at the fuel-shell interface.

Paediatric hand fractures

This retrospective study reviews the demographics, morphology and management of paediatric hand fractures. Notes of all children with hand injuries attending a plastic surgery paediatric trauma clinic over a one-year period were reviewed. Non-bony injuries were excluded. A total of 303 fractures in 283 patients were included. Fracture incidence rose after the age of seven, peaking at 14 years of age; 76% of fractures occurred in males. Sporting injuries accounted for 47% of fractures. Physeal fractures were present in 39% of cases. Open fractures accounted for only 4% of all fractures. Management was primarily conservative. Only 5% of cases required surgical fixation; 6% of patients experienced complications.

Solid-supported chemiluminescence and electrogenerated chemiluminescence based on a tris(2,2′-bipyridyl)ruthenium(ii) derivative

We report a simple and efficient technique for the covalent immobilisation of a tris(2,2'-bipyridyl)ruthenium(II) derivative suitable for both chemiluminescence and electrochemiluminescence detection.

Comparative analysis of thaumatin crystals grown on earth and in microgravity

The protein thaumatin was studied as a model macromolecule for crystallization in microgravity-environment experiments conducted on two US Space Shuttle missions (USML-2 and LMS). In this investigation, we have evaluated and compared the quality of space- and earth-grown thaumatin crystals using X-ray diffraction analyses, and characterized them according to crystal size, diffraction resolution limit and mosaicity. Two different approaches for growing thaumatin crystals in the microgravity environment, dialysis and liquid-liquid diffusion, were employed as a joint experiment by our two investigative teams. Thaumatin crystals grown in a microgravity environment were generally larger in volume and the total number of crystals was less, relative to crystals grown on earth. They diffracted to significantly higher resolution and with improved diffraction properties, as judged by relative plots of I/sigma versus resolution. The mosaicity of space-grown crystals was significantly less than that of crystals grown on earth. Increased concentrations of protein in the crystallization chambers in microgravity led to larger crystals. The data presented here lend further support to the idea that protein crystals of improved quality can be obtained in a microgravity environment.

Structures of three crystal forms of the sweet protein thaumatin

Three crystal forms of the sweet-tasting protein thaumatin from the African berry Thaumatococcus daniellii have been grown. These include two naturally occurring isoforms, A and B, that differ by a single amino acid, and a recombinant form of isoform B expressed in yeast. The crystals are of space groups C2 with a = 117.7, b = 44.9, c = 38.0 A, and beta = 94.0 degrees, P2(1)2(1)2(1) with a = 44.3, b = 63.7 and c = 72.7 A, and a tetragonal form P4(1)2(1)2 with a = b = 58.6 and c = 151.8 A. The structures of all three crystals have been solved by molecular replacement and subsequently refined to R factors of 0.184 for the monoclinic at 2.6 A, 0.165 for the orthorhombic at 1.75 A, and 0.181 for the tetragonal, also at 1.75 A resolution. No solvent was included in the monoclinic crystal while 123 and 105 water molecules were included in the higher resolution orthorhombic and tetragonal structures, respectively. A bound tartrate molecule was also clearly visible in the tetragonal structure. The r.m.s. deviations between molecular structures in the three crystals range from 0.6 to 0.7 A for Calpha atoms, and 1.1 to 1.3 A for all atoms. This is comparable to the r.m.s. deviation between the three structures and the starting model. Nevertheless, several peptide loops show particularly large variations from the initial model.

Susceptibility of young offenders to measles and rubella: an antibody prevalence study using oral fluid samples

Three hundred and two oral fluid samples collected in January 2001 from male young offenders aged 18 to 21 years at HMP Hindley were screened for measles and rubella specific IgG, using 'in-house' amplified ELISA assays. MMR (measles/mumps/rubella) vaccine, offered at the same time, was accepted by 68.1% of the prisoners (92.7% of those agreeing to oral fluid antibody testing). Antibody prevalences were 92.1% for rubella and 80.8% for measles. This may, however, underestimate true prevalence as the sensitivity of the oral fluid assays used may be relatively poor in adults. Susceptibility levels are theoretically high enough to result in outbreaks should either infection enter this closed institutional environment. Since a measles outbreak would carry significant morbidity and rubella would represent a risk to associated non-immune women of childbearing age, it is suggested that prison health services should offer MMR to young offenders on entry.

Changing the system: a quality management approach to pressure injuries

The quality management (QM) department at a large integrated healthcare system developed a methodology for preventing, predicting, and treating pressure injuries across the continuum, from acute care to long-term care to home care. The initiative, the first recipient of the Ernest A. Codman Award of the Joint Commission on Accreditation of Healthcare Organizations in the network category, resulted in decreased incidence and severity of pressure injuries, reduced length of stay, and significant cost savings to the system. The process the department used illustrates how an innovative QM program can facilitate change and institute a uniform standard of care.

Structural transitions of satellite tobacco mosaic virus particles

Satellite tobacco mosaic virus (STMV) can undergo at least two physical transitions that significantly alter its mechanical and structural characteristics. At high pH the 17-nm STMV particles expand radially by about 5 A to yield particles having diameters of about 18 nm. This pH-induced transition is further promoted by aging of the virions and degradation of the RNA, so that swollen particles ultimately appear even at neutral pH. While the native 17-nm particles crystallize as orthorhombic or monoclinic crystals which diffract to high resolution (1.8 A), the enlarged 18-nm particles crystallize in a cubic form which diffracts to no better than 5 A. In the transition, not only do the capsid protein subunits move radially outward, but the helical RNA segments with which they interact do as well. This is noteworthy because it demonstrates that the RNA and the protein shell are capable of coordinated movement, and that neither structure is rigidly defined or independent of the other. Using atomic force microscopy, it can be shown that STMV particles, upon drying, lose their mechanical rigidity and undergo deformation. Virions initially 17 nm in diameter shrink to more uniform final sizes than do 18 nm, initially swollen particles. This transition appears to be irreversible, as the particles do not reassume their former size nor structural rigidity upon rehydration. Evidence is also presented that preparations of native virus and their crystals are naturally somewhat heterogeneous and contain a variety of particles of anomalous size.

Biophysical studies on the RNA cores of satellite tobacco mosaic virus

Satellite tobacco mosaic virus (STMV) was probed using a variety of proteases. Consequences of the degradation were analyzed using gel electrophoresis, quasi-elastic light scattering (QELS), and atomic force microscopy (AFM). Proteolysis rates of 30 minutes for complete degradation of the protein capsid, up to many hours, were investigated. With each protease, degradation of virions 17 nm in diameter was shown by QELS to result in particles of 10 nm diameter, which is that of the RNA core observed in the virion by x-ray diffraction analysis. This was verified by direct visualization with atomic force microscopy. Using QELS, it was further shown that freshly prepared RNA cores remain as individual, stable, 10-nm condensed particles for 12 to 24 h. Clusters of particles then formed, followed by very large aggregates of 500 to 1000 nm diameter. AFM showed that the aggregates were composed of groups of the condensed RNA cores and were not due to unfolding of the nucleic acid. No unfolding of the core particles into extended conformation was seen by AFM until the samples were heated well beyond 90 degrees C. Mass spectrometry of RNA core particles revealed the presence of a major polypeptide whose amino acid sequence corresponded to residues 2 through 25 of the coat protein. Amino acids 13 through 25 were previously observed to be in direct contact with the RNA and are presumably protected from protease digestion. Low resolution difference Fourier analyses indicated the courses of the remainders of the amino terminal strands (amino acids 2-12) in intact virions. Any individual strand appears to have several choices of path, which accounts for the observed disorder at high resolution. These positively charged strands, serving as virtual polyamines, engage the helical segments of RNA. The intimate association of amino acid residues 2 through 25 with RNA likely contributes to the stability of the condensed conformation of the nucleic acid cores.

Season of birth is not associated with delayed childhood mortality in Upper River Division, The Gambia

There is evidence that season of birth may predict adult mortality from infectious diseases in rural Gambia. Using data collected over a five-year period from the rural, eastern region of the Gambia, we examined whether the season of birth influences mortality in childhood. 26 894 births and 3776 deaths among children under the age of five years were recorded in this region during the period 1989-1993. The estimated 1-4 year population was 95 355. In children aged 1-4 years, the mortality rate per 1000 per year was 16.1 (95% CI 14.9, 17.2) for those born in the 'harvest' season (January to June), which was not significantly different from the rate of 17.9 (95% CI 16.7, 19.0) recorded for those born in the 'hungry' season (July to December) (age-stratified Mantel-Haenszel mortality ratio 0. 91, 95% CI 0.83, 1.01; p = 0.08). Nearly all deaths of 1-4 year olds were attributed to infectious diseases, with malaria accounting for over 40%. None of the cause-specific child mortality rates differed significantly according to the season of birth. These data suggest that beyond infancy, when it is easier to separate the effect of season on cause of death from that of the season of birth, there is no marked difference in the rate of death between Gambian children born in the harvest season and those born in the hungry season.

Refined structure of desmodium yellow mottle tymovirus at 2.7 A resolution

Desmodium yellow mottle virus is a 28 nm diameter, T=3 icosahedral plant virus of the tymovirus group. Its structure has been solved to a resolution of 2.7 A using X-ray diffraction analysis based on molecular replacement and phase extension methods. The final R value was 0.151 (R(free)=0.159) for 134,454 independent reflections. The folding of the polypeptide backbone is nearly identical with that of turnip yellow mosaic virus, as is the arrangement of subunits in the virus capsid. However, a major difference in the disposition of the amino-terminal ends of the subunits was observed. In turnip yellow mosaic virus, those from the B and C subunits comprising the hexameric capsomeres formed an annulus about the interior of the capsomere, while the corresponding N termini of the pentameric capsomere A subunits were not visible at all in electron density maps. In Desmodium yellow mottle tymovirus, amino termini from the A and B subunits combine to form the annuli, thereby resulting in a much strengthened association between the two types of capsomeres and an, apparently, more stable capsid. The first 13 residues of the C subunit were invisible in electron density maps. Two ordered fragments of single-stranded RNA, seven and two nucleotides in length, were observed. The ordered water structure of the virus particle was delineated and required 95 solvent molecules per protein subunit.

Combining GUM and contraceptive services for young people: profile of an innovative clinic.(GUM = genitourinary medicine)

The 1990s have witnessed a growth in specialist family planning provision for adolescents including advisory clinics for young people. However there has been no parallel development of teenager-friendly genitourinary medicine (GUM) services despite the prevalence of sexually transmitted disease (STDs) in the adolescent age group. This article profiles a young person's clinic in Morecambe, UK which operates a combined family planning/GUM clinic one night a week in a multi-agency, 'shop front', youth project. Attendances are high, particularly amongst young teenagers and males. The clinic enjoys a 66 per cent follow up rate and 11 per cent of clients had crossed over from one service to the other on succeeding visits. Seventeen cases of chlamydia had been diagnosed, nine to females under 18. The benefits of a 'one stop' clinic and the youth project location are discussed.

Causes of mortality in twins in a rural region of The Gambia, West Africa

Little is known about birth or mortality rates of twins in The Gambia. There are no reports of the causes of death among twins in sub-Saharan Africa. We identified twin births and deaths from a community-based study which had been carried out in a large rural region of The Gambia over a 5-year period from 1989 to 1993. The overall twinning rate excluding stillbirths was 14.3 (95% CI 12.9, 15.8) per 1000 live deliveries. This was significantly lower among the Mandinka ethnic group (8.8 per 1000) than among the Serahulis (15.1 per 1000) or Fulas (18.3 per 1000). The early-neonatal, late-neonatal and post-neonatal twin mortality rates were 114.0, 45.9 and 64.2 per 1000 live twin births, respectively. In comparison, the early-neonatal, late-neonatal and post-neonatal mortality rates of singletons were 18.6, 16.0 and 41.1 per 1000, respectively. In the post-neonatal period, malnutrition was more frequently a cause of death among twins than among singletons (7.8 per 1000 twin births vs 2.0 per 1000 singleton births; p = 0.0008). Appropriate strategies for preventing malnutrition are required for this high-risk group.

Refined structure of satellite tobacco mosaic virus at 1.8 A resolution

The molecular structure of satellite tobacco mosaic virus (STMV) has been refined to 1.8 A resolution using X-ray diffraction data collected from crystals grown in microgravity. The final R value was 0.179 and Rfree was 0.184 for 219,086 independent reflections. The final model of the asymmetric unit contained amino acid residues 13 to 159 of a coat protein monomer, 21 nucleotides, a sulfate ion, and 168 water molecules. The nucleotides were visualized as 30 helical segments of nine base-pairs with an additional base stacked at each 3' end, plus a "free" nucleotide, not belonging to the helical segments, but firmly bound by the protein. Sulfate ions are located exactly on 5-fold axes and each is coordinated by ten asparagine side-chains. Of the 10,080 structural waters, 168 per asymmetric unit, about 20% serve to bridge the macromolecular components at protein-protein and protein-nucleic acid interfaces. Binding of RNA to the protein involves some salt linkages, particularly to the phosphate of the free nucleotide, but the major contribution is from an intricate network of hydrogen bonds. There are numerous water molecules in the RNA-protein interface, many serving as intermediate hydrogen bond bridges. The sugar-phosphate backbone contributes most of the donors and acceptors for the RNA. The helical RNA conformation is nearest that of A form DNA. The central region of a helical segment is most extensively involved in contacts with protein, and exhibits low thermal parameters which increase dramatically toward the ends. The visible RNA represents approximately 59% of the total nucleic acid in the virion and is derived from the single-stranded genome, which has folded upon itself to form helical segments. Linking of the helices and the free nucleotides in a contiguous and efficient manner severely restricts the disposition of the remaining, unseen nucleic acid. Using the remaining nucleotides it is possible to fold the RNA according to motifs that provide a periodic distribution of RNA structural elements compatible with the icosahedrally symmetrical arrangement seen in the crystallographic structure. The intimate relationship between protein and nucleic acid in STMV suggests an assembly pathway based on the cooperative and coordinated co-condensation of RNA with capsid protein dimers.

Comparative analysis of thaumatin crystals grown on earth and in microgravity

The protein thaumatin was studied as a model macro-molecule for crystallization in microgravity-environment experiments conducted on two US Space Shuttle missions (USML-2 and LMS). In this investigation, we have evaluated and compared the quality of space- and earth-grown thaumatin crystals using X-ray diffraction analyses, and characterized them according to crystal size, diffraction resolution limit and mosaicity. Two different approaches for growing thaumatin crystals in the microgravity environment, dialysis and liquid-liquid diffusion, were employed as a joint experiment by our two investigative teams. Thaumatin crystals grown in a microgravity environment were generally larger in volume and the total number of crystals was less, relative to crystals grown on earth. They diffracted to significantly higher resolution and with improved diffraction properties, as judged by relative plots of I/sigma versus resolution. The mosaicity of space-grown crystals was significantly less than that of crystals grown on earth. Increased concentrations of protein in the crystallization chambers in microgravity led to larger crystals. The data presented here lend further support to the idea that protein crystals of improved quality can be obtained in a microgravity environment.

The crystallographic structure of the subtilisin protease from Penicillium cyclopium

The major extracellular protease from the fungus Pencillium cyclopium was crystallized in the presence of p-phenylmethanesulfonyl fluoride (PMSF) and investigated by X-ray diffraction analysis. It was subsequently cloned and the amino acid sequence deduced from its cDNA. Although the sequence is only 49% identical to that of proteinase K of Tritirachium album, the three-dimensional structures of the two proteases are virtually identical. The model for P. cyclopium protease was refined by simulated annealing to an R of 18% at 1.7 A resolution. The greatest variation from the proteinase K polypeptide is in loop 114-134 and is due to the absence of a disulfide bridge in the P. cyclopium protease that is present in proteinase K. A difference was also observed in the orientation of the histidine in the catalytic triad, though this could be due to the presence of PMSF at the active site. The coordination geometry of the strongly bound calcium in the P. cyclopium protease is octahedral and uses some different protein ligands than does proteinase K. In the protease from P. cyclopium there is no cysteine near the active site, nor is there a second calcium binding site as is found in proteinase K, suggesting that neither is important to catalytic activity.