Drug-Related Hyponatremic Encephalopathy: Rapid Clinical Response Averts Life-Threatening Acute Cerebral Edema.

BACKGROUND: Drug-induced hyponatremia characteristically presents with subtle psychomotor symptoms due to its slow onset, which permits compensatory volume adjustment to hypo-osmolality in the central nervous system. Due mainly to the syndrome of inappropriate antidiuretic hormone secretion (SIADH), this condition readily resolves following discontinuation of the responsible pharmacological agent. Here, we present an unusual case of life-threatening encephalopathy due to adverse drug-related effects, in which a rapid clinical response facilitated emergent treatment to avert life-threatening acute cerebral edema. CASE REPORT: A 63-year-old woman with refractory depression was admitted for inpatient psychiatric care with a normal physical examination and laboratory values, including a serum sodium [Na+] of 144 mEq/L. She had a grand mal seizure and became unresponsive on the fourth day of treatment with the dual serotonin and norepinephrine reuptake inhibitor [SNRI] duloxetine while being continued on a thiazide-containing diuretic for a hypertensive disorder. Emergent infusion of intravenous hypertonic (3%) saline was initiated after determination of a serum sodium [Na+] of 103 mEq/L with a urine osmolality of 314 mOsm/kg H20 and urine [Na+] of 12 mEq/L. Correction of hyposmolality in accordance with current guidelines resulted in progressive improvement over several days, and she returned to her baseline mental status. CONCLUSIONS: Seizures with life-threatening hyponatremic encephalopathy in this case likely resulted from co-occurring SIADH and sodium depletion due to duloxetine and hydrochlorothiazide, respectively. A rapid clinical response expedited diagnosis and emergent treatment to reverse life-threatening acute cerebral edema and facilitate a full recovery without neurological complications.

Options for inactivation, adjuvant, and route of topical administration of a killed, unencapsulated pneumococcal whole-cell vaccine.

We previously reported that ethanol-killed cells of a noncapsulated strain of Streptococcus pneumoniae, given intranasally with cholera toxin as an adjuvant, protect rats against pneumonia and mice against colonization of the nasopharynx and middle ear by capsulated pneumococci of various serotypes. The acceleration of pneumococcal clearance from the nasopharynx in mice is CD4+ T cell-dependent and interleukin 17A (IL-17A) mediated and can be antibody independent. Here, anticipating human studies, we have demonstrated protection with a new vaccine strain expressing a nonhemolytic derivative of pneumolysin and grown in bovine-free culture medium. Killing the cells with chloroform, trichloroethylene, or beta-propiolactone--all used without postinactivation washing--produced more-potent immunogens than ethanol, and retention of soluble components released from the cells contributed to protection. Two sequential intranasal administrations of as little as 1 microg of protein (total of cellular and soluble combined) protected mice against nasopharyngeal challenge with pneumococci. Nontoxic single and double mutants of Escherichia coli heat-labile toxin were effective as mucosal adjuvants. Protection was induced by the sublingual and buccal routes, albeit requiring larger doses than when given intranasally. Protection was likewise induced transdermally with sonicates of the killed-cell preparation. Thus, this whole-cell antigen can be made and administered in a variety of ways to suit the manufacturer and the vaccination program and is potentially a solution to the need for a low-cost vaccine to reduce the burden of childhood pneumococcal disease in low-income countries.

Protection against Pneumococcal colonization and fatal pneumonia by a trivalent conjugate of a fusion protein with the cell wall polysaccharide.

Cell wall polysaccharide (CWPS), pneumolysin, and surface adhesin A (PsaA) are antigens common to virtually all serotypes of Streptococcus pneumoniae (pneumococcus), and all have been studied separately for use in protection. Previously we showed that protection against nasopharyngeal (NP) colonization by intranasal vaccination of mice with killed pneumococci is mediated by T(H)17 cells and correlates with interleukin-17A (IL-17A) expression by T cells in vitro; we have also shown that CWPS and other species-common antigens protect against colonization by a similar mechanism. Here we made a fusion protein of PsaA with the pneumolysin nontoxic derivative PdT and then coupled CWPS to the fusion protein, aiming to enhance immune responses to all three antigens. When given intranasally with cholera toxin adjuvant, the fusion conjugate induced higher serum antibody titers and greater priming for IL-17A responses than an equimolar mixture of the three antigens. The conjugate administered intranasally protected mice against experimental NP colonization by a strain of serotype 6B, while mice immunized with the mixture or with bivalent conjugates were not protected. Subcutaneous immunization with the conjugate and alum adjuvant likewise induced higher antibody titers than the mixture, primed for IL-17A responses, and reduced colonization. The conjugate, but not the antigen mixture, fully protected mice from fatal pneumonia caused by a highly virulent serotype 3 strain. Thus, a covalent construct of three antigens common to all serotypes exhibits protection with both mucosal and systemic administration.

Interleukin-17A mediates acquired immunity to pneumococcal colonization.

Although anticapsular antibodies confer serotype-specific immunity to pneumococci, children increase their ability to clear colonization before these antibodies appear, suggesting involvement of other mechanisms. We previously reported that intranasal immunization of mice with pneumococci confers CD4+ T cell-dependent, antibody- and serotype-independent protection against colonization. Here we show that this immunity, rather than preventing initiation of carriage, accelerates clearance over several days, accompanied by neutrophilic infiltration of the nasopharyngeal mucosa. Adoptive transfer of immune CD4+ T cells was sufficient to confer immunity to naïve RAG1(-/-) mice. A critical role of interleukin (IL)-17A was demonstrated: mice lacking interferon-gamma or IL-4 were protected, but not mice lacking IL-17A receptor or mice with neutrophil depletion. In vitro expression of IL-17A in response to pneumococci was assayed: lymphoid tissue from vaccinated mice expressed significantly more IL-17A than controls, and IL-17A expression from peripheral blood samples from immunized mice predicted protection in vivo. IL-17A was elicited by pneumococcal stimulation of tonsillar cells of children or adult blood but not cord blood. IL-17A increased pneumococcal killing by human neutrophils both in the absence and in the presence of antibodies and complement. We conclude that IL-17A mediates pneumococcal immunity in mice and probably in humans; its elicitation in vitro could help in the development of candidate pneumococcal vaccines.