Third-Generation Cephalosporin-Resistant Vibrio cholerae, India

Vibrio cholerae resistance to third-generation cephalosporins is rarely reported. We detected a strain that was negative for extended-spectrum β-lactamase and positive for the AmpC disk test, modified Hodge test, and EDTA disk synergy test and harbored the blaDHA-1 and blaNDM-1 genes. The antimicrobial drug susceptibility profile of V. cholerae should be monitored.     

Comparison of risk prediction scoring systems for ward patients: a retrospective nested case-control study

Introduction

The rising prevalence of rapid response teams has led to a demand for risk-stratification tools that can estimate a ward patient’s risk of clinical deterioration and subsequent need for intensive care unit (ICU) admission. Finding such a risk-stratification tool is crucial for maximizing the utility of rapid response teams. This study compares the ability of nine risk prediction scores in detecting clinical deterioration among non-ICU ward patients. We also measured each score serially to characterize how these scores changed with time.

Methods

In a retrospective nested case-control study, we calculated nine well-validated prediction scores for 328 cases and 328 matched controls. Our cohort included non-ICU ward patients admitted to the hospital with a diagnosis of infection, and cases were patients in this cohort who experienced clinical deterioration, defined as requiring a critical care consult, ICU admission, or death. We then compared each prediction score’s ability, over the course of 72 hours, to discriminate between cases and controls.

Results

At 0 to 12 hours before clinical deterioration, seven of the nine scores performed with acceptable discrimination: Sequential Organ Failure Assessment (SOFA) score area under the curve of 0.78, Predisposition/Infection/Response/Organ Dysfunction Score of 0.76, VitalPac Early Warning Score of 0.75, Simple Clinical Score of 0.74, Mortality in Emergency Department Sepsis of 0.74, Modified Early Warning Score of 0.73, Simplified Acute Physiology Score II of 0.73, Acute Physiology and Chronic Health Evaluation II of 0.72, and Rapid Emergency Medicine Score of 0.67. By measuring scores over time, it was found that average SOFA scores of cases increased as early as 24 to 48 hours prior to deterioration (P = 0.01). Finally, a clinical prediction rule which also accounted for the change in SOFA score was constructed and found to perform with a sensitivity of 75% and a specificity of 72%, and this performance is better than that of any SOFA scoring model based on a single set of physiologic variables.

Conclusions

ICU- and emergency room-based prediction scores can also be used to prognosticate risk of clinical deterioration for non-ICU ward patients. In addition, scoring models that take advantage of a score’s change over time may have increased prognostic value over models that use only a single set of physiologic measurements.     

Pharmacokinetics and Pharmacodynamics of (+)-Primaquine and (?)-Primaquine Enantiomers in Rhesus Macaques (Macaca mulatta)

Primaquine (PQ) remains the sole available drug to prevent relapse of Plasmodium vivax malaria more than 60 years after licensure. While this drug was administered as a racemic mixture, prior studies suggested a pharmacodynamic advantage based on differential antirelapse activity and/or toxicities of its enantiomers. Oral primaquine enantiomers prepared using a novel, easily scalable method were given for 7 days to healthy rhesus macaques in a dose-rising fashion to evaluate their effects on the blood, liver, and kidneys. The enantiomers were then administered to Plasmodium cynomolgi-infected rhesus macaques at doses of 1.3 and 0.6 mg/kg of body weight/day in combination with chloroquine. The (−)-PQ enantiomer had higher clearance and apparent volume of distribution than did (+)-PQ and was more extensively converted to the carboxy metabolite. There is evidence for differential oxidative stress with a concentration-dependent rise in methemoglobin (MetHgb) with increasing doses of (+)-PQ greater than that seen for (−)-PQ. There was a marked, reversible hepatotoxicity in 2 of 3 animals dosed with (−)-PQ at 4.5 mg/kg. (−)-PQ in combination with chloroquine was successful in preventing P. cynomolgi disease relapse at doses of 0.6 and 1.3 mg/kg/day, while 1 of 2 animals receiving (+)-PQ at 0.6 mg/kg/day relapsed. While (−)-PQ was also associated with hepatotoxicity at higher doses as seen previously, this has not been identified as a clinical concern in humans during >60 years of use. Limited evidence for increased MetHgb generation with the (+) form in the rhesus macaque model suggests that it may be possible to improve the therapeutic window for hematologic toxicity in the clinic by separating primaquine into its enantiomers.     

Humanized mouse model of glucose 6-phosphate dehydrogenase deficiency for in vivo assessment of hemolytic toxicity

Individuals with glucose 6-phosphate dehydrogenase (G6PD) deficiency are at risk for the development of hemolytic anemia when given 8-aminoquinolines (8-AQs), an important class of antimalarial/antiinfective therapeutics. However, there is no suitable animal model that can predict the clinical hemolytic potential of drugs. We developed and validated a human (hu)RBC-SCID mouse model by giving nonobese diabetic/SCID mice daily transfusions of huRBCs from G6PD-deficient donors. Treatment of SCID mice engrafted with G6PD-deficient huRBCs with primaquine, an 8-AQ, resulted in a dose-dependent selective loss of huRBCs. To validate the specificity of this model, we tested known nonhemolytic antimalarial drugs: mefloquine, chloroquine, doxycycline, and pyrimethamine. No significant loss of G6PD-deficient huRBCs was observed. Treatment with drugs known to cause hemolytic toxicity (pamaquine, sitamaquine, tafenoquine, and dapsone) resulted in loss of G6PD-deficient huRBCs comparable to primaquine. This mouse model provides an important tool to test drugs for their potential to cause hemolytic toxicity in G6PD-deficient populations.Glucose-6-phosphate dehydrogenase (G6PD) deficiency is the most common human enzyme deficiency, with an estimated 400 million people worldwide affected by this enzymopathy (1). G6PD-deficient RBCs are uniquely sensitive to oxidative stress. Several drugs induce oxidative stress in G6PD-deficient RBCs, including the antimalarial drug primaquine (PQ), an 8-aminoquinoline (8-AQ) (2). The damaged G6PD-deficient RBCs are subsequently cleared from the peripheral circulation, resulting in “hemolytic” anemia (2). 8-AQs are the only approved drug class able to eliminate the hypnozoite stages of the malaria parasite (3), as well as stage V Plasmodium falciparum gametocytes (4, 5). These characteristics make them an ideal drug class for malaria elimination campaigns (6, 7). However, because of the hemolytic toxicity associated with PQ, this drug has sharply limited utility in public health programs for the treatment of malaria. Although new 8-AQs have been developed (8), the lack of a relevant animal model to predict hemolytic toxicity in the context of G6PD deficiency has hindered further development of this class of antimalarial drugs (2).SCID mice have routinely been used as models of human disease (9–12). Lacking in functional immune responses, and therefore able to accept xenogenic transplants, SCID mice have been widely used as hosts for the engraftment of both normal and malignant human cells including human RBCs (huRBCs) (13, 14). Subsequent studies on the engraftment of huRBCs improved the degree and persistence of engraftment by using sublethal irradiation, chemical treatment protocols, or inclusion of denatured human serum and repeated administration of huRBCs to enhance engraftment efficiency (15–18). Recent advances in the development of immunodeficient mouse models have yielded mice with higher engraftment capacities and with minimal manipulation before engraftment. SCID mice developed on the nonobese diabetic (NOD) background (NOD/SCID) are able to support huRBCs for prolonged periods after repeated i.p. injections of huRBCs (19–21).We report here the development of an NOD/SCID mouse model engrafted with G6PD-deficient huRBCs. Treatment with PQ and other drugs known to induce hemolytic anemia in humans produced hemolytic responses in mice engrafted with G6PD-deficient huRBCs, suggesting that this model can be used for testing drugs for the prediction of the hemolytic toxicity. Use of this model will expedite the development of safer drugs for malaria treatment and prophylaxis, as well as other antiparasitic diseases for which 8-AQs have demonstrated efficacy.     

Transducin translocation contributes to rod survival and enhances synaptic transmission from rods to rod bipolar cells

In rod photoreceptors, several phototransduction components display light-dependent translocation between cellular compartments. Notably, the G protein transducin translocates from rod outer segments to inner segments/spherules in bright light, but the functional consequences of translocation remain unclear. We generated transgenic mice where light-induced transducin translocation is impaired. These mice exhibited slow photoreceptor degeneration, which was prevented if they were dark-reared. Physiological recordings showed that control and transgenic rods and rod bipolar cells displayed similar sensitivity in darkness. After bright light exposure, control rods were more strongly desensitized than transgenic rods. However, in rod bipolar cells, this effect was reversed; transgenic rod bipolar cells were more strongly desensitized than control. This sensitivity reversal indicates that transducin translocation in rods enhances signaling to rod bipolar cells. The enhancement could not be explained by modulation of inner segment conductances or the voltage sensitivity of the synaptic Ca²⁺ current, suggesting interactions of transducin with the synaptic machinery.     

Larvicidal activity of green synthesized silver nanoparticles using bark aqueous extract of Ficus racemosa against Culex quinquefasciatus and Culex gelidus

ObjectiveTo investigate the larvicidal activity of synthesized silver nanoparticles (Ag NPs) utilizing aqueous bark extract of Ficus racemosa (F. racemosa) was tested against fourth instar larvae of filariasis vector, Culex quinquefasciatus (Cx. quinquefasciatus) and japanese encephalitis vectors, Culex gelidus (Cx. gelidus).MethodsThe synthesized Ag NPs was characterized by UV-vis spectrum, X-ray diffraction (XRD), Scanning electron microscopy (SEM) and Fourier transform infrared (FTIR). The larvicidal activities were assessed for 24 h against the larvae of Cx. quinquefasciatus and Cx. gelidus with varying concentrations of aqueous bark extract of F. racemosa and synthesized Ag NPs. LC₅₀ and r² values were calculated.ResultsThe maximum efficacy was observed in crude aqueous extract of F. racemosa against the larvae of Cx. quinquefasciatus and Cx. gelidus (LC₅₀=67.72 and 63.70 mg/L; r²=0.995 and 0.985) and the synthesized Ag NPs (LC₅₀=12.00 and 11.21 mg/L; r²=0.997 and 0.990), respectively. Synthesized Ag NPs showed the XRD peaks at 2 θ values of 27.61, 29.60, 35.48, 43.48 and 79.68 were identified as (210), (121), (220), (200) and (311) reflections, respectively. The FTIR spectra of Ag NPs exhibited prominent peaks at 3 425, 2 878, 1 627 and 1 382 in the region 500-3 000 cm^?1. The peaks correspond to the presence of a stretching vibration of (NH) C=O group. SEM analysis showed shape in cylindrical, uniform and rod with the average size of 250.60 nm.ConclusionsThe biosynthesis of silver nanoparticles using bark aqueous extract of F. racemosa and its larvicidal activity against the larvae of disease spreading vectors. The maximum larvicidal efficacy was observed in the synthesized Ag NPs.     

Early experience with the ross procedure

Five patients have undergone replacement of the aortic root and valve with a pulmonary autograft. The right ventricular outflow tract was reconstructed with a homograft pulmonary or aortic valve. Technical details and relevance of this procedure in India are highlighted.     

Predisposing factors in the Spondyloarthropathies: New insights into the role of HLA-B27

Spondyloarthropathies represent complex genetic diseases whose development is influenced by environmental factors. Estimates suggest that three to nine loci may be responsible for the majority of the genetic susceptibility to ankylosing spondylitis. The only susceptibility locus identified to date in multiple populations is HLA-B, where several HLA-B27 alleles (subtypes) are strongly associated with disease. Recent evidence implicates cytochrome P450 2D6 as a second locus, although its influence on overall risk appears small. Despite considerable efforts to define how HLA-B27 contributes to disease, its role remains enigmatic. Increasing evidence suggests it has effects that are unrelated to its physiologic function. The basis for this is unknown but may be a consequence of the unusual tendency of this allele to misfold.