Early Indicators of Fatal Leptospirosis during the 2010 Epidemic in Puerto Rico

Background

Leptospirosis is a potentially fatal bacterial zoonosis that is endemic throughout the tropics and may be misdiagnosed as dengue. Delayed hospital admission of leptospirosis patients is associated with increased mortality.

Methodology/Principal Findings

During a concurrent dengue/leptospirosis epidemic in Puerto Rico in 2010, suspected dengue patients that tested dengue-negative were tested for leptospirosis. Fatal and non-fatal hospitalized leptospirosis patients were matched 1:1–3 by age. Records from all medical visits were evaluated for factors associated with fatal outcome. Among 175 leptospirosis patients identified (4.7 per 100,000 residents), 26 (15%) were fatal. Most patients were older males and had illness onset during the rainy season. Fatal case patients first sought medical care earlier than non-fatal control patients (2.5 vs. 5 days post-illness onset [DPO], p < 0.01), but less frequently first sought care at a hospital (52.4% vs. 92.2%, p < 0.01). Although fatal cases were more often diagnosed with leptospirosis at first medical visit (43.9% vs. 9.6%, p = 0.01), they were admitted to the hospital no earlier than non-fatal controls (4.5 vs. 6 DPO, p = 0.31). Cases less often developed fever (p = 0.03), but more often developed jaundice, edema, leg pain, hemoptysis, and had a seizure (p ≤ 0.03). Multivariable analysis of laboratory values from first medical visit associated with fatal outcome included increased white blood cell (WBC) count with increased creatinine (p = 0.001), and decreased bicarbonate with either increased WBC count, increased creatinine, or decreased platelet count (p < 0.001).

Conclusions/Significance

Patients with fatal leptospirosis sought care earlier, but were not admitted for care any earlier than non-fatal patients. Combinations of routine laboratory values predictive of fatal outcome should be considered in admission decision-making for patients with suspected leptospirosis.     

STING Millennium Suite: integrated software for extensive analyses of 3d structures of proteins and their complexes

Background  

The integration of many aspects of protein/DNA structure analysis is an important requirement for software products in general area of structural bioinformatics. In fact, there are too few software packages on the internet which can be described as successful in this respect. We might say that what is still missing is publicly available, web based software for interactive analysis of the sequence/structure/function of proteins and their complexes with DNA and ligands. Some of existing software packages do have certain level of integration and do offer analysis of several structure related parameters, however not to the extent generally demanded by a user.     

Structural basis for Chk1 inhibition by UCN-01

Chk1 is a serine-threonine kinase that plays an important role in the DNA damage response, including G(2)/M cell cycle control. UCN-01 (7-hydroxystaurosporine), currently in clinical trials, has recently been shown to be a potent Chk1 inhibitor that abrogates the G(2)/M checkpoint induced by DNA-damaging agents. To understand the structural basis of Chk1 inhibition by UCN-01, we determined the crystal structure of the Chk1 kinase domain in complex with UCN-01. Chk1 structures with staurosporine and its analog SB-218078 were also determined. All three compounds bind in the ATP-binding pocket of Chk1, producing only slight changes in the protein conformation. Selectivity of UCN-01 toward Chk1 over cyclin-dependent kinases can be explained by the presence of a hydroxyl group in the lactam moiety interacting with the ATP-binding pocket. Hydrophobic interactions and hydrogen-bonding interactions were observed in the structures between UCN-01 and the Chk1 kinase domain. The high structural complementarity of these interactions is consistent with the potency and selectivity of UCN-01.     

A novel dynein light intermediate chain colocalizes with the retrograde motor for intraflagellar transport at sites of axoneme assembly in chlamydomonas and Mammalian cells

The assembly of cilia and flagella depends on bidirectional intraflagellar transport (IFT). Anterograde IFT is driven by kinesin II, whereas retrograde IFT requires cytoplasmic dynein 1b (cDHC1b). Little is known about how cDHC1b interacts with its cargoes or how it is regulated. Recent work identified a novel dynein light intermediate chain (D2LIC) that colocalized with the mammalian cDHC1b homolog DHC2 in the centrosomal region of cultured cells. To see whether the LIC might play a role in IFT, we characterized the gene encoding the Chlamydomonas homolog of D2LIC and found its expression is up-regulated in response to deflagellation. We show that the LIC subunit copurifies with cDHC1b during flagellar isolation, dynein extraction, sucrose density centrifugation, and immunoprecipitation. Immunocytochemistry reveals that the LIC colocalizes with cDHC1b in the basal body region and along the length of flagella in wild-type cells. Localization of the complex is altered in a collection of retrograde IFT and length control mutants, which suggests that the affected gene products directly or indirectly regulate cDHC1b activity. The mammalian DHC2 and D2LIC also colocalize in the apical cytoplasm and axonemes of ciliated epithelia in the lung, brain, and efferent duct. These studies, together with the identification of an LIC mutation, xbx-1(ok279), which disrupts retrograde IFT in Caenorhabditis elegans, indicate that the novel LIC is a component of the cDHC1b/DHC2 retrograde IFT motor in a variety of organisms.     

Ultrastructure of Mikrocytos mackini, the cause of Denman Island disease in oysters Crassostrea spp. and Ostrea spp. in British Columbia, Canada

An ultrastructural study was carried out on Mikrocytos mackini, the cause of Denman Island disease in Pacific oysters Crassostrea gigas in western Canada. Three forms were identified, quiescent cells (QC), vesicular cells (VC) and endosomal cells (EC). QC occurred in the vesicular connective tissue (VCT), haemocytes (hyalinocytes), adductor and heart myocytes, and extracellularly. They had a central round to ovoid nucleus, < 7 cisternae of inactive nuclear membrane-bound Golgi, few vesicles and lysosome-like bodies. VC were rarely extracellular and usually occurred in adductor and heart myocytes, in close association with host cell mitochondria. The contents of the host cell mitochondria appeared to pass through a tubular extension into the cytoplasm of the parasite. Cytoplasmic vesicles resembled the tubular structure in appearance and size. EC occurred in the VCT, in haemocytes and extracellularly. They had a dilated nuclear membrane, sometimes containing a looped membranous structure that appeared to derive from the nucleus, and pass into the cytoplasm. A well-developed anastomosing endoplasmic reticulum connected the nuclear and plasma membranes, and endosomes were present in the cytoplasm. QC and EC cells were frequently observed tightly against, or between, the nuclear membranes of the host cell. Few organelles occurred in all forms of M. mackini, especially QC. The lack of organelles found in most eukaryotic cells, including mitochondria or their equivalents, may be due to obligate parasitism and the utilization of host cell organelles reducing the need for parasite organelles. Alternatively, perhaps M. mackini is a primitive eukaryote. Although phylogenetic affinities could not be determined, it is not a haplosporidian. A developmental cycle is proposed from these findings.     

Activity losses among T4 lysozyme variants after adsorption to colloidal silica

Maintaining a specific molecular conformation is essential for the proper functioning of an enzyme. A substantial loss of catalytic activity can occur from the displacement caused by even a single amino acid substitution. Activity may also be lost as an enzyme undergoes a conformational change during adsorption. In this study, we investigated the effect of thermostability on the activities of three T4 lysozyme variants after adsorption to 9 nm colloidal silica particles. Less-stable T4 lysozyme variants lost more activity after adsorption than did more stable variants, apparently because they experienced more extensive structural alteration.     

Enhancement of optical coherence microscopy in turbid media by an optical parametric amplifier

We report the enhancement in imaging performance of a spectral‐domain optical coherence microscope (OCM) in turbid media by incorporating an optical parametric amplifier (OPA). The OPA provides a high level of optical gain to the sample arm, thereby improving the signal‐to‐noise ratio of the OCM by a factor of up to 15 dB. A unique nonlinear confocal gate is automatically formed in the OPA, which enables selective amplification of singly scattered (ballistic) photons against the multiply‐scattered light background. Simultaneous enhancement in both imaging depth and spatial resolution in imaging microstructures in highly light‐scattering media are demonstrated with the combined OPA‐OCM setup.

Typical OCM inteferograms (left) and images (right) without and with OPA.