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Observations of magnetic clouds, within interplanetary coronal mass ejections (ICMEs), are often well described by flux rope models. Most of these assume either a cylindrical or toroidal geometry. In some cases, these models are also capable of accounting for non‐axisymmetric cross‐sections but they generally all assume axial invariance. It can be expected that any ICME, and its flux rope, will be deformed along its axis due to influences such as the solar wind. In this work, we aim to develop a writhed analytical magnetic flux rope model which would allow us to analytically describe a flux rope structure with varying curvature and torsion so that we are no longer constrained to a cylindrical or toroidal geometry. In this first iteration of our model we will solely focus on a circular cross‐section of constant size. We describe our flux rope geometry in terms of a parametrized flux rope axis and a parallel transport frame. We derive expressions for the axial and poloidal magnetic field components under the assumption that the total axial magnetic flux is conserved. We find an entire class of possible solutions, which differ by the choice of integration constants, and present the results for a specific example. In general, we find that the twist of the magnetic field locally changes when the geometry deviates from a cylinder or torus. This new approach also allows us to generate completely new types of in situ magnetic field profiles which strongly deviate from those generated by cylindrical or toroidal models. Key Points: We develop an analytical model that can be used to describe writhed flux ropes by describing the flux rope axis as a general space curveWe show how this model can be implemented numerically in terms of quadratic splines and configured for an arbitrary twist distributionWe find that the field lines resulting from our model have lower twist per unit length than would be expected from a toroidal approximation [ABSTRACT FROM AUTHOR]

Interplanetary coronal mass ejections (ICMEs) are one of the main drivers for space weather disturbances. In the past, different approaches have been used to automatically detect events in existing time series resulting from solar wind in situ observations. However, accurate and fast detection still remains a challenge when facing the large amount of data from different instruments. For the automatic detection of ICMEs we propose a pipeline using a method that has recently proven successful in medical image segmentation. Comparing it to an existing method, we find that while achieving similar results, our model outperforms the baseline regarding training time by a factor of approximately 20, thus making it more applicable for other datasets. The method has been tested on in situ data from the Wind spacecraft between 1997 and 2015 with a True Skill Statistic of 0.64. Out of the 640 ICMEs, 466 were detected correctly by our algorithm, producing a total of 254 false positives. Additionally, it produced reasonable results on datasets with fewer features and smaller training sets from Wind, STEREO‐A, and STEREO‐B with TSSs of 0.56, 0.57, and 0.53, respectively. Our pipeline manages to find the start of an ICME with a mean absolute error (MAE) of around 2 hr and 56 min, and the end time with a MAE of 3 hr and 20 min. The relatively fast training allows straightforward tuning of hyperparameters and could therefore easily be used to detect other structures and phenomena in solar wind data, such as corotating interaction regions. Plain Language Summary: Interplanetary coronal mass ejections (ICMEs) are part of space weather and can have severe effects on human technology. Since the detection of these events is often difficult, experts are usually needed to detect them in time series from different spacecraft. Even though, there have been attempts to solve this problem using machine learning, it is far from being solved. We propose a machine learning model, that manages to find the start and end times with improved accuracy and takes less time to train. Even though our results are quite promising, it is important to notice that there are many different catalogs documenting ICMEs, that do not always agree. Therefore, there is no unique solution to this problem, which makes it difficult for a machine learning method to learn the features of an ICME. Nevertheless, our model can be expected to make a substantial contribution to the area of space weather forecast in the future. Key Points: We automatically detect interplanetary coronal mass ejections in solar wind in situ dataWe achieve a True Skill Statistic of 0.64, Recall of 0.67 and Precision of 0.70 on data from WindWe propose a pipeline generally applicable to time series event detection problems [ABSTRACT FROM AUTHOR]

The forecasting of local GIC effects has largely relied on the forecasting of dB/dt as a proxy and, to date, little attention has been paid to directly forecasting the geoelectric field or GICs themselves. We approach this problem with machine learning tools, specifically recurrent neural networks or LSTMs by taking solar wind observations as input and training the models to predict two different kinds of output: first, the geoelectric field components Ex and Ey; and second, the GICs in specific substations in Austria. The training is carried out on the geoelectric field and GICs modeled from 26 years of one-minute geomagnetic field measurements, and results are compared to GIC measurements from recent years. The GICs are generally predicted better by an LSTM trained on values from a specific substation, but only a fraction of the largest GICs are correctly predicted. This model has a correlation with measurements of around 0.6, and a root-mean-square error of 0.7 A. The probability of detecting mild activity in GICs is around 50%, and 15% for larger GICs. [ABSTRACT FROM AUTHOR]

Geomagnetically induced currents (GICs), a result of solar wind interaction with the Earth's magnetic field and the resistive ground, are known to flow in power transmission grids, where they can lead to transformer damage and grid operation problems. In this study we present an analysis of five years of continuous GIC measurements in transformer neutral points in Austria. Seven self‐designed stand‐alone measurement systems are currently installed in the Austrian 220 and 380 kV transmission levels, measuring currents up to 25 A. We identify recurrent geomagnetic activity in the measurements, and also find man‐made sources of low frequency currents using frequency analysis. In order to support the transmission grid operators, two GIC simulation approaches are used to simulate GICs in the power grid. The first model uses measurements to derive the sensitivity of the location to northward and eastward geoelectric field components (which requires no detailed grid data), and the second model uses the detailed grid model to compute GICs from a geoelectric field. We evaluate two geomagnetic storms from September 2017 and May 2021 to discuss the effects of GICs on the power transmission grid and its assets. Plain Language Summary: During geomagnetic storms, rapid changes in the Earth's magnetic field induce an electric field in the ground, may drive currents in the power grid. These are called geomagnetically induced currents (GICs) and they can lead to power grid operation problems and even transformer damage. In this study we present learning's from five years of GIC measurements in Austria, which have been carried out in seven different transformers in the grid. Some power grid transformers show larger susceptibility than other transformers to magnetic field variations accompanied by larger GICs. We also identify some of the sources of noise in the data such as a city subway system, and investigate two geomagnetic storms from September 2017 and May 2021 in more detail. Key Points: Measurements of geomagnetically induced currents (GICs) in power grid substation transformers have been carried out since September 2016 in AustriaWe summarize the measurements until now and discuss data quality and sources of noiseA statistical analysis of GIC measurements, a comparison of simulation models for two storms and an attempt to a risk assessment is performed [ABSTRACT FROM AUTHOR]

Predicting the Bz magnetic field embedded within interplanetary coronal mass ejections (ICMEs), also known as the Bz problem, is a key challenge in space weather forecasting. We study the hypothesis that upstream in situ measurements of the sheath region and the first few hours of the magnetic obstacle provide sufficient information for predicting the downstream Bz component. To do so, we develop a predictive tool based on machine learning that is trained and tested on 348 ICMEs from Wind, STEREO‐A, and STEREO‐B measurements. We train the machine learning models to predict the minimum value of the Bz component and the maximum value of the total magnetic field Bt in the magnetic obstacle. To validate the tool, we let the ICMEs sweep over the spacecraft and assess how continually feeding in situ measurements into the tool improves the Bz prediction. We specifically find that the predictive tool can predict the minimum value of the Bz component in the magnetic obstacle with a mean absolute error of 3.12 nT and a Pearson correlation coefficient of 0.71 when the sheath region and the first 4 hr of the magnetic obstacle are observed. While the underlying hypothesis is unlikely to solve the Bz problem, the tool shows promise for ICMEs that have a recognizable magnetic flux rope signature. Transitioning the tool to operations could lead to improved space weather forecasting. Plain Language Summary: At any time, our solar system is populated with interplanetary coronal mass ejections (ICMEs). Solar scientists and space weather forecasters track ICMEs when they are ejected from the Sun and follow their path into the vast reaches of interplanetary space. They do so because if an ICME hits Earth, it could damage our infrastructure such as power‐grids and GPS satellites, which are a mainstay of our modern civilization. The possible damage is primarily determined by the magnetic field embedded within the ICME. The North‐South magnetic field component, Bz, plays a decisive role, especially if it is pointing opposite to Earth's magnetic field. Currently we cannot predict Bz with sufficient accuracy. Scientists often refer to our limited predictive abilities as the Bz problem. Here we shine a new light on the Bz problem by developing a predictive tool based on machine learning that is trained and tested on 348 ICMEs. By feeding measurements of the ICME into machine learning algorithms, we find that our predictive tool can forecast the Bz component reasonably well. While our tool does not solve the Bz problem, it shows promise in forecasting and potentially mitigating the effects of ICMEs on our planet Earth and its inhabitants. Key Points: We hypothesize that upstream in situ measurements are sufficient to predict Bz in solar coronal mass ejectionsWe present a predictive tool that forecasts the minimum of Bz in an interplanetary coronal mass ejections with a MAE of 3.12 nT and a pearson correlation coefficient of 0.71 [ABSTRACT FROM AUTHOR]

Studying the ambient solar wind, a continuous pressure-driven plasma flow emanating from our Sun, is an important component of space weather research. The ambient solar wind flows in interplanetary space determine how solar storms evolve through the heliosphere before reaching Earth, and especially during solar minimum are themselves a driver of activity in the Earth's magnetic field. Accurately forecasting the ambient solar wind flow is therefore imperative to space weather awareness. Here, we present a machine learning approach in which solutions from magnetic models of the solar corona are used to output the solar wind conditions near the Earth. The results are compared to observations and existing models in a comprehensive validation analysis, and the new model outperforms existing models in almost all measures. In addition, this approach offers a new perspective to discuss the role of different input data to ambient solar wind modeling, and what this tells us about the underlying physical processes. The final model discussed here represents an extremely fast, well-validated and open-source approach to the forecasting of ambient solar wind at Earth. [ABSTRACT FROM AUTHOR]

Geomagnetic storms resulting from high‐speed streams can have significant negative impacts on modern infrastructure due to complex interactions between the solar wind and geomagnetic field. One measure of the extent of this effect is the Kyoto Dst index. We present a method to predict Dst from data measured at the Lagrange 5 (L5) point, which allows for forecasts of solar wind development 4.5 days in advance of the stream reaching the Earth. Using the STEREO‐B satellite as a proxy, we map data measured near L5 to the near‐Earth environment and make a prediction of the Dst from this point using the Temerin‐Li Dst model enhanced from the original using a machine learning approach. We evaluate the method accuracy with both traditional point‐to‐point error measures and an event‐based validation approach. The results show that predictions using L5 data outperform a 27‐day solar wind persistence model in all validation measures but do not achieve a level similar to an L1 monitor. Offsets in timing and the rapidly changing development of Bz in comparison to Bx and By reduce the accuracy. Predictions of Dst from L5 have a root‐mean‐square error of 9 nT, which is double the error of 4 nT using measurements conducted near the Earth. The most useful application of L5 measurements is shown to be in predicting the minimum Dst for the next 4 days. This method is being implemented in a real‐time forecast setting using STEREO‐A as an L5 proxy and has implications for the usefulness of future L5 missions. Key Points: In situ L5 data can be used for Dst forecasts at Earth and perform better than 27‐day persistenceLow consistency ofBz over multiple days limits the accuracy of Dst predicted from L5This method performs best when forecasting the minimum Dst during SIRs [ABSTRACT FROM AUTHOR]

Abstract: Space weather events can cause geomagnetically induced currents (GICs) in power transmission networks. Over the past years, these currents have been measured in multiple substations in Austria, and the measurements have been tested against a model of local GIC with the aim of producing an optimized model, which can be developed through evaluation of various input parameters. We show the impact the choice of the local resistivity, in particular the surface conductivity in thin‐sheet modeling, and the source of geomagnetic variations has on GIC modeling. In addition, the sensitivity of the model to the accuracy of the network configuration is also investigated. This encompasses the inclusion of power grids outside of Austria in the model as well as the consequences of removal of a substation either through transformer failure or active disconnection. Results show that a detailed surface conductivity model brings benefits to areas with large lateral conductivity variations and that there are certain substations that lead to increases and decreases of GIC in the rest of the network when removed. The importance of regionally representative geomagnetic field measurements is also highlighted and shown to impact model accuracy. This study concentrates on regional effects, but the results are also valid for large‐scale studies elsewhere. [ABSTRACT FROM AUTHOR]

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Tumor necrosis factor (TNF) is thought to be a key mediator of the inflammatory and fibrotic response to Chlamydia trachomatis (Ct) infection. A large matched-pair case–control study investigated putative functional single nucleotide polymorphisms (SNPs) across the major histocompatibility complex (MHC) class III region, including TNF and its immediate neighbors nuclear factor of κ light polypeptide gene enhancer in B cells (IκBL), inhibitor like 1 and lymphotoxin alpha (LTA) in relation to the risk of scarring sequelae of ocular Ct infection. Haplotype and linkage disequilibrium analysis demonstrated two haplotypes, differing at position TNF-308, conferring an increased risk of trichiasis. The TNF-308A allele, and its bearing haplotype, correlated with increased TNF production in lymphocyte cultures stimulated with chlamydial elementary body antigen. Thus TNF-308A may determine directly, or be a marker of a high TNF producer phenotype associated with increased risk of sequelae of chlamydial infection. Multivariate analysis provided evidence for the presence of additional risk-associated variants near the TNF locus.Genes and Immunity (2007) 8, 288–295; doi:10.1038/sj.gene.6364384; published online 1 March 2007 [ABSTRACT FROM AUTHOR]

Ocular chlamydial disease is clinically diagnosed by the appearance of characteristic inflammatory changes and development of lymphoid follicles in the conjunctiva. Nucleic acid amplification tests and relatively non-invasive methods of sampling the conjunctival surface can be used to quantify the expression of chlamydial and host genes. Using quantitative real-time polymerase chain reaction to detect the presence of Chlamydia trachomatis (CT) 16S rRNA and human interleukin (IL)-1β, IL-10, IL-12p40, interferon (IFN)-γ and tumour necrosis factor (TNF)-α transcripts we examined the immune response at the conjunctival surface in a cohort of children living in a trachoma-endemic village in The Gambia. Elevated cytokine transcript levels were associated with the presence of CT 16S rRNA. Subclinical infection (CT infection without clinical signs of disease) elicited an immune response that is proinflammatory in nature, with elevations in the transcription of IL-1β, IFN-γ and IL-12p40. Clinically apparent infections were associated with the elevation of mRNA for the multi-functional cytokine TNF-α (fibrotic, type 1 inflammatory and regulatory) and the counter regulatory cytokine, IL-10, in addition to the other proinflammatory cytokines. A positive correlation between IFN-γ transcript levels and the amount of CT 16S rRNA expressed in conjunctiva was found. [ABSTRACT FROM AUTHOR]

Background/aim: Trachomatous trichiasis frequently returns following surgery. Several factors may promote recurrence: preoperative disease severity, surgeon ability, surgical procedure, healing responses, and infection. This study investigates whether enhanced control of infection, both of Chlamydia trachomatis and other bacteria, with azithromycin can improve surgical outcome in a trachoma control programme. Methods: Individuals with trachomatous trichiasis were examined and operated. After surgery patients were randomised to the azithromycin or control group. The azithromycin group and children in their household were given a dose of azithromycin. Antibiotic treatment was repeated at 6 months. All patients were reassessed at 6 months and 12 months. Samples were collected for C trachomatis polymerase chain reaction and general microbiology at each examination. Results: 451 patients were enrolled. 426 (94%) were reassessed at 1 year, of whom 176 (41.3%) had one or more lashes touching the eye and 84 (19.7%) had five or more lashes. There was no difference in trichiasis recurrence between the azithromycin and control group. Recurrent trichiasis was significantly associated with more severe preoperative trichiasis, bacterial infection, and severe conjunctival inflammation at 12 months. Significant variability in outcome was found between surgeons. Visual acuity and symptoms significantly improved following surgery. Conclusion: In this selling, with a low prevalence of active trachoma, azithromycin did not improve the outcome of trichiasis surgery conducted by a trachoma control programme. Audit of trichiasis surgery should be routine. [ABSTRACT FROM AUTHOR]

Experimental evidence implicates interferon gamma (IFN?) in protection from and resolution of chlamydial infection. Conversely, interleukin 10 (IL10) is associated with susceptibility and persistence of infection and pathology. We studied genetic variation within the IL10 and IFN?loci in relation to the risk of developing severe complications of human ocular Chlamydia trachomatis infection. A total of 651 Gambian subjects with scarring trachoma, of whom 307 also had potentially blinding trichiasis and pair-matched controls with normal eyelids, were screened for associations between single-nucleotide polymorphisms (SNPs), SNP haplotypes and the risk of disease. MassEXTEND (Sequenom) and MALDI-TOF mass spectrometry were used for detection and analysis of SNPs and the programs PHASE and SNPHAP used to infer haplotypes from population genetic data. Multivariate conditional logistic regression analysis identified IL10 and IFN?SNP haplotypes associated with increased risk of both trachomatous scarring and trichiasis. SNPs in putative IFN?and IL10 regulatory regions lay within the disease-associated haplotypes. The IFN?+874A allele, previously linked to lower IFN?production, lies in the IFN?risk haplotype and was more common among cases than controls, but not significantly so. The promoter IL10-1082G allele, previously associated with high IL10 expression, is in both susceptibility and resistance haplotypes.Genes and Immunity (2005) 6, 332-340. doi:10.1038/sj.gene.6364182 Published online 24 March 2005 [ABSTRACT FROM AUTHOR]

SUMMARY The circulating and cervical B cell responses to Chlamydia trachomatis plasmid protein pgp3 were characterized in children and adults with ocular or genital chlamydial infection using the enzyme-linked immunospot assay (ELISPOT) and ELISA. No pgp3-specific ASCs were detected in healthy controls, but predominantly IgA ASCs were detected in UK adults with uncomplicated cervicitis or urethritis (P = 0·03, 0·019). In patients with extragenital complications or pelvic inflammatory disease a mixed response with more IgG and IgM ASCs was evident, suggesting a breach of mucosal immune compartmentalization with more extensive infection. In women with chlamydial cervicitis, ASCs secreting predominantly IgA, but also IgG, to pgp3 were present in cervix at presentation, with a frequency 30–50 times higher than blood. Cervical ASC numbers, especially IgG, fell markedly six weeks after antibiotic treatment. We detected principally IgA pgp3-specific antibody secreting cells (ASCs) in children resident in a Gambian endemic area, with a trend towards suppression of IgA responses during intense trachomatous inflammation (P = 0·06), as previously reported for other chlamydial antigens, and in keeping with the findings in genital disease. These data provide a rationale for further studies of immune responses to pgp3 in humans and animal models of chlamydia-induced disease, and its potential use in diagnostic assays and protective immunization strategies. [ABSTRACT FROM AUTHOR]

Abstract. The fly Musca sorbens Wiedemann (Diptera: Muscidae) apparently transmits Chlamydia trachomatis, causing human trachoma. The literature indicates that M. sorbens breeds predominantly in isolated human faeces on the soil surface, but not in covered pit latrines. We sought to identify breeding media of M. sorbens in a rural Gambian village endemic for trachoma. Test breeding media were presented for oviposition on soil-filled buckets and monitored for adult emergence. Musca sorbens emerged from human (6/9 trials), calf (3/9), cow (3/9), dog (2/9) and goat (1/9) faeces, but not from horse faeces, composting kitchen scraps or a soil control (0/9 of each). After adjusting for mass of medium, the greatest number of flies emerged from human faeces (1426 flies/kg). Median time for emergence was 9 (inter quartile range = 8–9.75) days post-oviposition. Of all flies emerging from faeces 81% were M. sorbens. Male and female flies emerging from human faeces were significantly larger than those from other media, suggesting that they would be more fecund and live longer than smaller flies from other sources. Female flies caught from children's eyes were of a similar size to those from human faeces, but significantly larger than those from other media. We consider that human faeces are the best larval medium for M. sorbens, although some breeding also occurs in animal faeces. Removal of human faeces from the environment, through the provision of basic sanitation, is likely to greatly reduce fly density, eye contact and hence trachoma transmission, but if faeces of other animals are present M. sorbens will persist. [ABSTRACT FROM AUTHOR]

The role of HLA-A*6802-restricted CD8+ T cells in chlamydial disease was investigated in human ocular infections. Peptides with predicted binding motifs for HLA-A*6802 were synthesized using sequences based on chlamydial antigens, major outer membrane protein (MOMP), macrophage infectivity potentiator (MIP) and heat shock protein (hsp70). Peptides were pooled according to Chlamydia trachomatis protein type and serovar, and were tested in 51Cr-release cytotoxic T lymphocyte (CTL) and enzyme-linked immunospot (ELISPOT) assays, using peripheral blood mononuclear cells (PBMC) isolated from subjects living in trachoma-endemic communities in The Gambia. Significant CTL activity or interferon-gamma release was not detected in any of the subjects, suggesting either that HLA-A*6802 CD8+ T cells may not be important in ocular infections or that the peptides chosen did not represent epitopes. [ABSTRACT FROM AUTHOR]

Community control of trachoma as a blinding disease is based on the SAFE strategy of Surgery, Antibiotic therapy, Facial cleanliness and Environmental improvement. Surgery and antibiotic therapy currently dominate most programmes. Blindness from trachoma results from frequent infections repeated over many years, so ultimate success requires the reduction of transmission. This is only likely to be sustainable through the F and E components of SAFE. Environmental improvement with access to water, enhanced hygiene and better sanitation reduces trachoma transmission and the blinding sequelae eventually disappear. Transmission routes and factors that cause this are not known and consequently no single specific tool for F and E is in place. Evidence from intervention studies shows that the promotion of face-washing gave modest gains for intense effort and a pilot study showed that trachoma transmission was reduced in the absence of eye-seeking flies. Other studies have shown that latrines and improved access to water are associated with a lower prevalence of active trachoma. There is likely to be a long-term beneficial effect of a combination of improved water supplies, provision of latrines, facial hygiene promotion through established infrastructure and control of eye-seeking flies. Each of these interventions offers additional public health and other benefits in its own right. Further research on the routes of transmission, the role of hygiene and means of sustainable fly control should be a priority. [ABSTRACT FROM AUTHOR]

Introduction: Surgery for trachomatous trichiasis prevents blindness and is advocated by the WHO as part of the SAFE strategy for the global elimination of trachoma. We conducted a randomised community trial to investigate the effect of providing surgery in villages on surgical uptake in The Gambia.Methods: 56 villages from two divisions were assigned to eight pairs of clusters matched by geographical division and proximity. One cluster from each pair was randomly assigned to receive village-based surgery and the other cluster health centre-based surgery. Outcome measures were uptake rates and surgical results after 1 week and 3 months. The paired t-test was used to analyse the results.Results: Overall uptake was 66% in the village-based clusters and 44% in the health centre-based clusters. Subjects in the village-based surgery arm had significantly shorter journey times (P = 0.01) and lower costs (P = 0.002). The mean difference in absolute acceptance rates of surgery was 20% better in village-based clusters (95% CI -9 to + 49%, P = 0.15), which would equate to an improvement of 45% (95% CI -20% to 120%) on the average acceptance rates of 44% in the health centre-based group.Conclusion: These results strongly suggest better surgical uptake when surgery is provided in patients' villages due to lower cost to the patient, time saved and less fear of the operation. [ABSTRACT FROM AUTHOR]

The application of a diagnostic and genotyping technique based on the polymerase chain reaction (PCR) to the study of trachoma epidemiology in the Gambian village of Jali is reported. PCR based on the major outer membrane protein (MOMP) gene of Chlamydia trachomatis appears to be more sensitive than either isolation or antigen detection by enzyme immunoassay; it had a specificity of 95% and sensitivity of 51% against clinical signs. PCR genotyping identified genotypes A and B of Chlamydia trachomatis circulating in Jali. Sequencing revealed a Pst1 restriction endonuclease site in the amplified MOMP gene of some B strains but not others; Pst1 digestion of the PCR product proved an easy method of distinguishing these strains. The distribution of serotypes and B strain variants shows a significant degree of household clustering (p < 0.001). PCR based genotyping combined with strain typing provides a new and powerful epidemiological tool for the study of transmission events in trachoma. [ABSTRACT FROM PUBLISHER]

CD8+ cytotoxic T lymphocytes (CTL) recognize peptide antigens in the context of class I MHC antigen molecules. To identify peptides capable of eliciting anti-Chlamydia trachomatis CTL responses, 13 synthetic peptides conforming to human leucocyte antigen (HLA)-B8- or -B35-predicted binding motifs were synthesized using sequences based on C. trachomatis major outer membrane protein (MOMP) and heat shock protein 60 (hsp60). Two of 11 HLA-B35-predicted binding peptides were able to stabilize HLA-B35 in an in vitro binding assay. All peptides were tested in CTL assays using peripheral blood mononuclear cells (PBMC) isolated from 26 HLA-B8 or -B35 individuals resident in a trachoma-endemic community. Responses to MOMP and hsp60 peptides were identified in a minority of both HLA-B8 and -B35 individuals. Two of 12 HLA-B8 subjects responded to MOMP and 1/13 to hsp60 peptides. Responses in HLA-B35 subjects were similar, 1/13 subjects responding to MOMP and 2/13 to hsp60 peptides. CTL responses were observed only in children resolving current infection and in adults without scarring of the conjunctiva. These results suggest that anti-chlamydial CTL occur at low levels in peripheral blood, but may be important in the resolution of naturally acquired human ocular chlamydial infection. [ABSTRACT FROM AUTHOR]

Increased stimulation of Th2 cytokines may contribute to the development of persistent ocular chlamydial infection, resulting in the blinding pathological changes of trachoma. Proliferation and cytokine production profiles of PBMC in response to stimulation with antigens of Chlamydia trachomatis were compared in 30 patients with severe conjunctival scarring due to trachoma and in 30 age-, sex-and location-matched controls. Interferon-gamma (IFN-γ) and IL-4 were detected at the single-cell level by ELISPOT assay. Transcription of the genes encoding IFN-γ, IL-4 and IL-10 was detected in mRNA isolated from parallel cultures of PBMC using reverse transcriptase-polymerase chain reaction (RT-PCR). Incubation with the chlamydial heat shock protein (hsp)60 resulted in increased numbers of lL-4-producing cells in PBMC isolated from patients with scarring disease and increased secretion of IFN-γ from PBMC of control subjects. Incubation with the chlamydial major outer membrane protein (MOMP) increased the number of IFN-γ-producing cells in the control group only. Messenger RNA encoding IL-4 was only detected in PBMC of patients with scarring disease after in vitro stimulation with chlamydial antigens, but (IFN-γ) mRNA and IL-10 mRNA were also more frequently detected in this group. Thirty-eight subjects were HLA-DRBI and -DQBI typed. Associations were observed between certain HLA class II alleles and cellular immune responses to chlamydial antigens. No HLA associations were found with clinical status, and overall we found no evidence of strong associations and the type of immune response. These data are consistent with a role for Th2 cells and cytokines in the pathogenesis of trachomatous scarring. [ABSTRACT FROM AUTHOR]

In an attempt to understand the pathogenesis of corneal changes and conjunctival scarring in trachoma, which are responsible for blindness in some 7 million people worldwide, the surface expression of major histocompatibility complex class II antigens on conjunctival epithelial cells was sought in patients with different clinical features of the disease. Class II expression was significantly associated with active (inflammatory) trachoma, but an independent association with corneal pannus or conjunctival scarring could not be shown. Longitudinal data suggest that class II expression may antedate clinically active disease and persist after it has resolved. [ABSTRACT FROM PUBLISHER]

To determine if serum antibody response to the 60-kDa chlamydial heat-shock protein (Chsp60) was associated with scarring trachoma, responses to Chlamydia trachomatis and to Chsp60 from 148 Gambian subjects with trachomatous scarring and from 148 controls without clinical evidence of disease from trachoma-endemic communities were characterized. Chsp60 response was found in 32%of cases and 16%of controls (P > .001). Although C. trachomatis titer was also higher in cases than controls, the prevalence of Chsp60 response between the 2 groups remained significantly different after stratifying for C. trachomatis titer (weighted odds ratio [OR] = 2.1, P = .02). Chsp60 response and C. trachomatis serovar A titer of ⩾ 128 were independently associated with scarring trachoma. The presence of HLA class II allele DRB1*0701 was positively correlated with Chsp60 response (OR = 2.6, P = .02), and DQB1*0301 and DQB1*0501 were negatively associated (OR = 0.42, P < .001; OR = 0.55, P = .46, respectively). [ABSTRACT FROM PUBLISHER]

Polymerase chain reaction (PCR) with primers derived from the sequence of the cryptic chlamydial plasmid was evaluated for the detection of ocular chlamydial infection in trachoma-endemic populations and was used to explore further the relationship between ocular chlamydial infection and clinical signs of trachoma. It was more sensitive than other laboratory techniques, especially for mild cases of trachoma, in detecting infection in 144 (72%) of 200 who fulfilled the World Health Organization case definition. Of 1132 subjects who did not fulfill these criteria, 85 (7.5%) were PCR-positive, but about one-third of these 85 subjects had minor signs of trachoma. Clinically negative subjects who were PCR-positive were more likely than PCR-negative subjects to have acquired signs of disease at 1 and 6 months of follow-up. Clinical signs were twice as likely to have resolved after 1 month in PCR-negative subjects with disease than in those who were PCR-positive. [ABSTRACT FROM PUBLISHER]

Background: Chlamydia trachomatis (Ct) is the most common infectious cause of blindness and bacterial sexually transmitted infection worldwide. Ct strain-specific differences in clinical trachoma suggest that genetic polymorphisms in Ct may contribute to the observed variability in severity of clinical disease. Methods: Using Ct whole genome sequences obtained directly from conjunctival swabs, we studied Ct genomic diversity and associations between Ct genetic polymorphisms with ocular localization and disease severity in a treatment-naïve trachoma-endemic population in Guinea-Bissau, West Africa. Results: All Ct sequences fall within the T2 ocular clade phylogenetically. This is consistent with the presence of the characteristic deletion in trpA resulting in a truncated non-functional protein and the ocular tyrosine repeat regions present in tarP associated with ocular tissue localization. We have identified 21 Ct non-synonymous single nucleotide polymorphisms (SNPs) associated with ocular localization, including SNPs within pmpD (odds ratio, OR = 4.07, p* = 0.001) and tarP (OR = 0.34, p* = 0.009). Eight synonymous SNPs associated with disease severity were found in yjfH (rlmB) (OR = 0.13, p* = 0.037), CTA0273 (OR = 0.12, p* = 0.027), trmD (OR = 0.12, p* = 0.032), CTA0744 (OR = 0.12, p* = 0.041), glgA (OR = 0.10, p* = 0.026), alaS (OR = 0.10, p* = 0.032), pmpE (OR = 0.08, p* = 0.001) and the intergenic region CTA0744–CTA0745 (OR = 0.13, p* = 0.043). Conclusions: This study demonstrates the extent of genomic diversity within a naturally circulating population of ocular Ct and is the first to describe novel genomic associations with disease severity. These findings direct investigation of host-pathogen interactions that may be important in ocular Ct pathogenesis and disease transmission. [ABSTRACT FROM AUTHOR]

Focuses on base-age invariance as a property of site-index curves as established by Bailey and Clutter. Data generated on the Ontario jack pine (Pinus banksiana); Predictions based on age and height of trees; How the curves produced by this model are not base-age invariant.

Mineral clouds in substellar atmospheres play a special role as a catalyst for a variety of charge processes. If clouds are charged, the surrounding environment becomes electrically activated, and ensembles of charged grains are electrically discharging (e.g., by lightning), which significantly influences the local chemistry creating conditions similar to those thought responsible for life in early planetary atmospheres. We note that such lightning discharges contribute also to the ionization state of the atmosphere. We apply scaling laws for electrical discharge processes from laboratory measurements and numerical experiments to DRIFT-PHOENIX model atmosphere results to model the discharge's propagation downward (as lightning) and upward (as sprites) through the atmospheric clouds. We evaluate the spatial extent and energetics of lightning discharges. The atmospheric volume affected (e.g., by increase of temperature or electron number) is larger in a brown dwarf atmosphere (108-1010 m3) than in a giant gas planet (104-106 m3). Our results suggest that the total dissipated energy in one event is <1012 J for all models of initial solar metallicity. First attempts to show the influence of lightning on the local gas phase indicate an increase of small carbohydrate molecules like CH and CH2 at the expense of CO and CH4. Dust-forming molecules are destroyed and the cloud particle properties are frozen in unless enough time is available for complete evaporation. We summarize instruments potentially suitable to observe lightning on extrasolar objects. [ABSTRACT FROM AUTHOR]

A correction to the article "Reproductive ecology of the azooxanthellate coral Tubastraea coccinea in the Equatorial Eastern Pacific: Part V. Dendrophyllidae" that was published in the February 16, 2008 issue is presented.

Clonal propagation of superior genotypes of commercially important forest trees via somatic embryogenesis has been hindered by a general inability to initiate embryogenic cultures from tissues of mature trees. We tested staminate inflorescences of sweetgum (Liquidambar styraciflua L.) as a source of cells that might be redetermined from theirdifferentiated state to an embryogenic state. Buds containing staminate inflorescences were collected from seven sweetgum clones at varying stages of elongation prior to and continuing through bud break. Inflorescence tissues were cultured on medium containing thidiazuron (TDZ) alone or in combination with 2,4-D. Although most cultures were lost to contamination or killed by disinfestation treatments, the least expanded inflorescences from buds of one clone produced eight independent embryogenic cultures following culture on 0.01--1 mg/L TDZ, either continuously or as a 1-week pulse followed by transfer to basal medium. Repetitive embryogenesis continued on medium containing 0.01 mg/L TDZ. While most embryos were malformed, embryos from two of the clones germinated on basal medium lacking casein hydrolysate, and germinants from one of these converted to plantlets that were acclimatized to greenhouse conditions. These preliminary results indicate that tissues from inflorescences of mature sweetgum trees have the abilityto produce embryogenic cultures, thus providing a potential route for large-scale cloning of superior genotypes. [ABSTRACT FROM AUTHOR]