Leptospirosis in pregnancy: A systematic review

IntroductionLeptospirosis is a leading zoonotic disease worldwide with more than 1 million cases in the general population per year. With leptospirosis being an emerging infectious disease and as the world’s environment changes with more floods and environmental disasters, the burden of leptospirosis is expected to increase. The objectives of the systematic review were to explore how leptospirosis affects pregnancy, its burden in this population, its effects on maternal and fetal outcomes and the evidence base surrounding treatment options.MethodsWe performed a systematic review of published and unpublished literature using automated and manual methods to screen nine electronic databases since inception, with no language restriction. Two reviewers independently screened articles, completed the data extraction and assessment of risk of bias. Due to significant heterogeneity and paucity of data, we were unable to carry out a meta-analysis, but we conducted a pooled analysis of individual patient data from the case reports and case series to examine the patient and disease characteristics, diagnostic methods, differential diagnoses, antibiotic treatments, and outcomes of leptospirosis in pregnancy. The protocol for this review was registered on the International Prospective Register of Systematic Reviews, PROSPERO: CRD42020151501.ResultsWe identified 419 records, of which we included eight observational studies, 21 case reports, three case series and identified four relevant ongoing studies. Overall the studies were with moderate bias and of ‘fair’ quality. We estimated the incidence of leptospirosis in pregnancy to be 1.3 per 10,000 in women presenting with fever or with jaundice, but this is likely to be higher in endemic areas. Adverse fetal outcomes were found to be more common in pregnant patients who presented in the second trimester compared with patients who presented in the third trimester. There is overlap between how leptospirosis presents in pregnancy and in the general population. There is also overlap between the signs, symptoms and biochemical disturbances associated with leptospirosis in pregnancy and the presentation of pregnancy associated conditions, such as Pre-Eclampsia (PET), Acute Fatty Liver of Pregnancy (AFLP) and HELLP Syndrome (Haemolysis Elevated Liver enzymes Low Platelets). In 94% of identified cases with available data, there was an indicator in the patient history regarding exposure that could have helped include leptospirosis in the clinician’s differential diagnosis. We also identified a range of suitable antibiotic therapies for treating leptospirosis in pregnancy, most commonly used were penicillins.ConclusionThis is the first systematic review of leptospirosis in pregnancy and it clearly shows the need to improve early diagnosis and treatment by asking early, treating early, and reporting well. Ask early—broaden differential diagnoses and ask early for potential leptospirosis exposures and risk factors. Treat early—increase index of suspicion in pregnant patients with fever in endemic areas and combine with rapid field diagnosis and early treatment. Report well—need for more good quality epidemiological studies on leptospirosis in pregnancy and better quality reporting of cases in literature.     

Targeting of antigen to the herpesvirus entry mediator augments primary adaptive immune responses

Interactions between the herpesvirus entry mediator (HVEM) and the B- and T-lymphocyte attenuator (BTLA) inhibit B and T cell activation. HVEM-BTLA interactions are blocked by herpes simplex virus (HSV) glycoprotein D (gD) through binding of its N-terminal domain to the BTLA binding site of HVEM. In this study, we inserted viral antigens into the C-terminal domain of gD and expressed these antigens with plasmid or E1-deleted (replication-defective) adenovirus vectors. Viral antigens fused to gD induced T and B cell responses to the antigen that were far more potent than those elicited by the same antigen expressed without gD. The immunopotentiating effect required binding of the gD chimeric protein to HVEM. Overall, the studies demonstrate that targeting of antigen to the BTLA binding site of HVEM augments the immunogenicity of vaccines.     

Negative Regulation of Syntaxin4/SNAP-23/VAMP2-Mediated Membrane Fusion by Munc18c In Vitro

Background

Translocation of the facilitative glucose transporter GLUT4 from an intracellular store to the plasma membrane is responsible for the increased rate of glucose transport into fat and muscle cells in response to insulin. This represents a specialised form of regulated membrane trafficking. Intracellular membrane traffic is subject to multiple levels of regulation by conserved families of proteins in all eukaryotic cells. Notably, all intracellular fusion events require SNARE proteins and Sec1p/Munc18 family members. Fusion of GLUT4-containing vesicles with the plasma membrane of insulin-sensitive cells involves the SM protein Munc18c, and is regulated by the formation of syntaxin 4/SNAP23/VAMP2 SNARE complexes.

Methodology/Principal Findings

Here we have used biochemical approaches to characterise the interaction(s) of Munc18c with its cognate SNARE proteins and to examine the role of Munc18c in regulating liposome fusion catalysed by syntaxin 4/SNAP23/VAMP2 SNARE complex formation. We demonstrate that Munc18c makes contacts with both t- and v-SNARE proteins of this complex, and directly inhibits bilayer fusion mediated by the syntaxin 4/SNAP23/VAMP2 SNARE complex.

Conclusion/Significance

Our reductionist approach has enabled us to ascertain a direct inhibitory role for Munc18c in regulating membrane fusion mediated by syntaxin 4/SNAP23/VAMP2 SNARE complex formation. It is important to note that two different SM proteins have recently been shown to stimulate liposome fusion mediated by their cognate SNARE complexes. Given the structural similarities between SM proteins, it seems unlikely that different members of this family perform opposing regulatory functions. Hence, our findings indicate that Munc18c requires a further level of regulation in order to stimulate SNARE-mediated membrane fusion.     

Tomosyn interacts with the t-SNAREs syntaxin4 and SNAP23 and plays a role in insulin-stimulated GLUT4 translocation

The Sec1p-like/Munc18 (SM) protein Munc18a binds to the neuronal t-SNARE Syntaxin1A and inhibits SNARE complex assembly. Tomosyn, a cytosolic Syntaxin1A-binding protein, is thought to regulate the interaction between Syntaxin1A and Munc18a, thus acting as a positive regulator of SNARE assembly. In the present study we have investigated the interaction between b-Tomosyn and the adipocyte SNARE complex involving Syntaxin4/SNAP23/VAMP-2 and the SM protein Munc18c, in vitro, and the potential involvement of Tomosyn in regulating the translocation of GLUT4 containing vesicles, in vivo. Tomosyn formed a high affinity ternary complex with Syntaxin4 and SNAP23 that was competitively inhibited by VAMP-2. Using a yeast two-hybrid assay we demonstrate that the VAMP-2-like domain in Tomosyn facilitates the interaction with Syntaxin4. Overexpression of Tomosyn in 3T3-L1 adipocytes inhibited the translocation of green fluorescent protein-GLUT4 to the plasma membrane. The SM protein Munc18c was shown to interact with the Syntaxin4 monomer, Syntaxin4 containing SNARE complexes, and the Syntaxin4/Tomosyn complex. These data suggest that Tomosyn and Munc18c operate at a similar stage of the Syntaxin4 SNARE assembly cycle, which likely primes Syntaxin4 for entry into the ternary SNARE complex.     

Temperature influences whole-animal rates of metabolism but not protein synthesis in a temperate intertidal isopod

The effects of temperature on two important biological rate processes, whole-body rates of oxygen uptake (M dot o2) and protein synthesis (k(s)), were investigated in the temperate intertidal isopod Ligia oceanica at two different times of the year. Animals were collected in January (winter) and June (summer) and either subjected to an acute temperature change after 24 h (acclimatized) or acclimated to various temperatures for 4 wk. In both cases, M dot o2 increased with temperature, with a Q(10) of 2.2 between 5 degrees and 20 degrees C, but increased in thermal sensitivity at 25 degrees C. Winter isopods were characterized by significantly higher M dot o2 levels, greater thermal sensitivities, and lower thermal tolerances than summer animals. Seasonal differences in M dot o2 persisted after acclimation, indicating that temperature alone was not responsible for the changes. In sharp contrast, whole-body k(s) showed no variation with temperature, although overall rates decreased upon acclimation. In acclimatized animals, k(s) was higher in the summer than in the winter. After acclimation, a compensatory increase in RNA capacity in winter animals reversed this situation. The temperature independence of whole-body k(s) in L. oceanica could ensure survival in a highly liable thermal environment, as thermal tolerances of intertidal invertebrates are thought to be more closely related to protein than to energy metabolism.     

A multi-enzyme model for Pyrosequencing

Pyrosequencing is a DNA sequencing technique based on sequencing-by-synthesis enabling rapid real-time sequence determination. This technique employs four enzymatic reactions in a single tube to monitor DNA synthesis. Nucleotides are added iteratively to the reaction and in case of incorporation, pyrophosphate (PPi) is released. PPi triggers a series of reactions resulting in production of light, which is proportional to the amount of DNA and number of incorporated nucleotides. Generated light is detected and recorded by a detector system in the form of a peak signal, which reflects the activity of all four enzymes in the reaction. We have developed simulations to model the kinetics of the enzymes. These simulations provide a full model for the Pyrosequencing four-enzyme system, based on which the peak height and shape can be predicted depending on the concentrations of enzymes and substrates. Simulation results are shown to be compatible with experimental data. Based on these simulations, the rate-limiting steps in the chain can be determined, and K_M and k_cat of all four enzymes in Pyrosequencing can be calculated.     

The role of alternative oxidase in modulating carbon use efficiency and growth during macronutrient stress in tobacco cells

When wild-type (wt) tobacco (Nicotiana tabacum cv. Petit Havana SR1) cells are grown under macronutrient (P or N) limitation, they induce large amounts of alternative oxidase (AOX), which constitutes a non-energy-conserving branch of the respiratory electron transport chain. To investigate the significance of AOX induction, wt cells were compared with transgenic (AS8) cells lacking AOX. Under nutrient limitation, growth of wt cell cultures was dramatically reduced and carbon use efficiency (g cell dry weight gain g(-1) sugar consumed) decreased by 42-63%. However, the growth of AS8 was only moderately reduced by the nutrient deficiencies and carbon use efficiency values remained the same as under nutrient-sufficient conditions. As a result, the nutrient limitations more severely compromised the tissue nutrient status (P or N) of AS8 than wt cells. Northern analyses and a comparison of the mitochondrial protein profiles of wt and AS8 cells indicated that the lack of AOX in AS8 under P limitation was associated with increased levels of proteins commonly associated with oxidative stress and/or stress injury. Also, the level of electron transport chain components was consistently reduced in AS8 while tricarboxylic acid cycle enzymes did not show a universal trend in abundance in comparison to the wt. Alternatively, the lack of AOX in AS8 cells under N limitation resulted in enhanced carbohydrate accumulation. It is concluded that AOX respiration provides an important general mechanism by which plant cells can modulate their growth in response to nutrient availability and that AOX also has nutrient-specific roles in maintaining cellular redox and carbon balance.     

Photosynthetic responses of plant communities to sand burial on the machair dune systems of the outer hebrides, Scotland

BACKGROUND AND AIMS: The effects of both short-term (2 weeks) and long-term (6 weeks) burial on the photosynthetic efficiency of four typical plant sub-communities of the machair sand dunes of the Outer Hebrides are described. Previous studies have examined the photosynthetic responses on individual species rather than the response at the community level. METHODS: Three replicate turves from four different sub-community types (foredune grassland, dune slack, three-year fallow and unploughed grassland) were subjected to short- and long-term burial treatments after acclimatisation in an unheated greenhouse for approximately 10 weeks. Three replicate control turves from each sub-community were left unburied. After treatment, photosynthetic rate was measured at 16-20 h and 40-44 h after re-exposure, using an infra-red gas analyser, with standardization by total leaf area for each turf. Effects of sub-community type, burial duration and time since re-exposure were analysed by 3-factor split-plot analysis of variance (ANOVA) with repeated measures for time since re-exposure in the subplots. KEY RESULTS: Buried turves were characterized by a low dark respiration rate, which may represent a maintenance response to burial. After removal of sand, each machair sub-community showed some capacity for an elastic photosynthetic response. There were no differences between the effects of short- and long-term burial on the photosynthetic efficiency of machair vegetation, although turves buried for 6 weeks generally attained photosynthetic rates approaching those of control rates sooner than turves buried for 2 weeks. Photosynthetic responses to burial varied between sub-communities, with the slack turves exhibiting the poorest capacity for recovery within the investigated 44-h period. CONCLUSIONS: In the machair environment, the ability to maintain photosynthetic equipment whilst buried, and the ability to bring about a relatively rapid reinstatement of photosynthetic mechanisms on emergence or exposure, is an important adaptation for survival. Survival is closely related to the ability of a plant to replenish carbohydrate reserves before the next burial event.     

A Copper10-Paclitaxel crystal; a medicinally active drug delivery platform

Paclitaxel is a well-known cancer drug that functions as a mitotic inhibitor. This work focuses on a copper based crystal that encapsulates the pharmaceutical agent and serves as a drug delivery agent. A Copper₁₀-Pacitaxil₁ chloride (CU₁₀PAC₁) complex is synthesized and tested against the National Cancer Institute’s sixty cell line panel. The 10:1 ratio results in a crystal that was examined by Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spec (MALDI-TOF-MS), Scanning Electron Microscopy (SEM) and Proton (¹H) and Carbon (¹³C) Nuclear Magnetic Resonance (NMR). The potential attributes of a copper based crystal as an in vivo drug carrier for Paclitaxel are discussed.     

Vacuole Biogenesis in Saccharomyces cerevisiae: Protein Transport Pathways to the Yeast Vacuole

Delivery of proteins to the vacuole of the yeast Saccharomyces cerevisiae provides an excellent model system in which to study vacuole and lysosome biogenesis and membrane traffic. This organelle receives proteins from a number of different routes, including proteins sorted away from the secretory pathway at the Golgi apparatus and endocytic traffic arising from the plasma membrane. Genetic analysis has revealed at least 60 genes involved in vacuolar protein sorting, numerous components of a novel cytoplasm-to-vacuole transport pathway, and a large number of proteins required for autophagy. Cell biological and biochemical studies have provided important molecular insights into the various protein delivery pathways to the yeast vacuole. This review describes the various pathways to the vacuole and illustrates how they are related to one another in the vacuolar network of S. cerevisiae.