The life cycle of the pathogen Leptospira interrogans involves stages outside and inside the host. Entry of L. interrogans from moist environments into the host is likely to be accompanied by the induction of genes encoding virulence determinants and the concomitant repression of genes encoding products required for survival outside of the host. The expression of the adhesin LigA, the haemolysin Sph2 (Lk73.5) and the outer-membrane lipoprotein LipL36 of pathogenic Leptospira species have been reported to be regulated by mammalian host signals. A previous study demonstrated that raising the osmolarity of the leptospiral growth medium to physiological levels encountered in the host by addition of various salts enhanced the levels of cell-associated LigA and LigB and extracellular LigA. In this study, we systematically examined the effects of osmotic upshift with ionic and non-ionic solutes on expression of the known mammalian host-regulated leptospiral genes. The levels of cell-associated LigA, LigB and Sph2 increased at physiological osmolarity, whereas LipL36 levels decreased, corresponding to changes in specific transcript levels. These changes in expression occurred irrespective of whether sodium chloride or sucrose was used as the solute. The increase of cellular LigA, LigB and Sph2 protein levels occurred within hours of adding sodium chloride. Extracellular Sph2 levels increased when either sodium chloride or sucrose was added to achieve physiological osmolarity. In contrast, enhanced levels of extracellular LigA were observed only with an increase in ionic strength. These results indicate that the mechanisms for release of LigA and Sph2 differ during host infection. Thus, osmolarity not only affects leptospiral gene expression by affecting transcript levels of putative virulence determinants but also affects the release of such proteins into the surroundings. INTRODUCTIONSpirochaetes of the genus Leptospira are a major cause of morbidity and mortality in developing nations (McBride et al., 2005). Leptospira interrogans is one of 14 genomospecies of pathogenic Leptospira and is the cause of endemic disease and large outbreaks of leptospirosis worldwide (Brenner et al., 1999;Levett et al., 2006). Outbreaks involving L. interrogans have been associated with flooding in rat-infested urban slums (Ko et al., 1999). L. interrogans resides chronically in the lumen of rat kidney tubules and is released within urine into the environment, where it can survive for weeks (Crawford et al., 1971;Gordon Smith & Turner, 1961;Ryu & Liu, 1966). Humans exposed to Leptospira in the environment can be infected through breaks in skin or mucous membranes. After breaching the epithelium or mucosa, leptospires migrate to the bloodstream and disseminate to numerous organs. Flulike symptoms including fever and myalgia characterize early acute-phase infection. Severe symptoms including Haake et al., 1998;Nally et al., 2001b). Recent microarray and proteomic experiments have revealed changes in the levels of numerous transcripts and s...

Leptospirosis is a widespread zoonosis caused by invasive spirochaetes belonging to the genus Leptospira. Pathogenic leptospires disseminate via the bloodstream to colonize the renal tubules of reservoir hosts. Little is known about leptospiral outer-membrane proteins expressed during the dissemination stage of infection. In this study, a novel surface-exposed lipoprotein is described; it has been designated LipL46 to distinguish it from a previously described 31 kDa peripheral membrane protein, P31 LipL45 , which is exported as a 45 kDa probable lipoprotein. The lipL46 gene encodes a 412 aa polypeptide with a 21 aa signal peptide. Lipid modification of cysteine at the lipoprotein signal peptidase cleavage site FSISC is supported by the finding that Leptospira interrogans intrinsically labels LipL46 during incubation in medium containing [14 C]palmitate.LipL46 appears to be exported to the leptospiral outer membrane as a 46 kDa lipoprotein, based on Triton X-114 solubilization and phase partitioning studies, which included the outer and inner membrane controls LipL32 and LipL31, respectively. Surface immunoprecipitation and whole-cell ELISA experiments indicate that LipL46 is exposed on the leptospiral surface.Immunohistochemistry studies demonstrated expression of LipL46 by leptospires found in the bloodstream of acutely infected hamsters. Leptospires expressing LipL46 were also found in the intercellular spaces of the liver, within splenic phagocytes, and invading the glomerular hilum of the kidney. Infection-associated expression is supported by the finding that LipL46 is a major antigen recognized by sera from infected hamsters. These findings indicate that LipL46 may be important in leptospiral dissemination, and that it may serve as a useful serodiagnostic antigen.

BACKGROUND: Malignant Hyperthermia (MH) is a potentially fatal, autosomal dominant disorder associated with administration of volatile anesthetics and/or the depolarizing paralytic succinylcholine. Symptoms include muscle rigidity, tachycardia, elevated body temperature, and metabolic acidosis, which are secondary to accelerated skeletal muscle metabolism. MH susceptibility can be a chronic condition, and some MH susceptible patients may develop symptoms subsequent to anesthetic exposure. OBJECTIVE: This is the first study examining the sequelae of an MH event after hospital discharge. METHODS: A survey was sent to patients who voluntarily registered with the North American Malignant Hyperthermia Registry, which included questions on severity of symptoms predominating prior to the MH event, one month after the MH event, and presently on a scale of 1 -10 with a free text option to expound further. Participants were also asked about their opinions on causality between MH and these symptoms. RESULTS: Twenty-three responses were analyzed (34.8% response rate). Participants were categorized by their age at the time of the MH event and years since the event. Most (83%) stayed in the ICU between 1 -4 days, and 39% experienced the event over 25 years ago. While 43% did not attribute any long-term symptoms to their MH event, all others believed that certain symptoms were linked, including muscle pain (90%), muscle cramps (75%), muscle weakness (100%), back/joint pain (36%) and depression/anxiety (42%). CONCLUSIONS: Our study concluded that long-lasting morbidities may be attributed to an MH event. Chronic musculoskeletal symptoms are experienced by the majority of patients who experience acute MH.