A nuclear protein, PfMORC confers melatonin dependent synchrony of the human malaria parasite P. falciparum in the asexual stage.

The host hormone melatonin is known to modulate the asexual cell-cycle of the human malaria parasite Plasmodium falciparum and the kinase PfPK7 is fundamental in the downstream signaling pathways. The nuclear protein PfMORC displays a histidine kinase domain and is involved in parasite cell cycle control. By using a real-time assay, we show a 24 h (h) rhythmic expression of PfMORC at the parasite asexual cycle and the expression is dramatically changed when parasites were treated with 100 nM melatonin for 17 h. Moreover, PfMORC expression was severely affected in PfPK7 knockout (PfPK7-) parasites following melatonin treatment. Parasites expressing 3D7morc-GFP shows nuclear localization of the protein during the asexual stage of parasite development. Although the PfMORC knockdown had no significant impact on the parasite proliferation in vitro it significantly changed the ratio of the different asexual intraerythrocytic stages of the parasites upon the addition of melatonin. Our data reveal that in addition to the upstream melatonin signaling pathways such as IP3 generation, calcium, and cAMP rise, a nuclear protein, PfMORC is essential for the hormone response in parasite synchronization.

Evidence for Regulation of Hemoglobin Metabolism and Intracellular Ionic Flux by the Plasmodium falciparum Chloroquine Resistance Transporter.

Plasmodium falciparum multidrug resistance constitutes a major obstacle to the global malaria elimination campaign. Specific mutations in the Plasmodium falciparum chloroquine resistance transporter (PfCRT) mediate resistance to the 4-aminoquinoline drug chloroquine and impact parasite susceptibility to several partner agents used in current artemisinin-based combination therapies, including amodiaquine. By examining gene-edited parasites, we report that the ability of the wide-spread Dd2 PfCRT isoform to mediate chloroquine and amodiaquine resistance is substantially reduced by the addition of the PfCRT L272F mutation, which arose under blasticidin selection. We also provide evidence that L272F confers a significant fitness cost to asexual blood stage parasites. Studies with amino acid-restricted media identify this mutant as a methionine auxotroph. Metabolomic analysis also reveals an accumulation of short, hemoglobin-derived peptides in the Dd2 + L272F and Dd2 isoforms, compared with parasites expressing wild-type PfCRT. Physiologic studies with the ionophores monensin and nigericin support an impact of PfCRT isoforms on Ca2+ release, with substantially reduced Ca2+ levels observed in Dd2 + L272F parasites. Our data reveal a central role for PfCRT in regulating hemoglobin catabolism, amino acid availability, and ionic balance in P. falciparum, in addition to its role in determining parasite susceptibility to heme-binding 4-aminoquinoline drugs.

Plasmodium falciparum GPCR-like receptor SR25 mediates extracellular K+ sensing coupled to Ca2+ signaling and stress survival.

The malaria parasite Plasmodium falciparum is exposed, during its development, to major changes of ionic composition in its surrounding medium. We demonstrate that the P. falciparum serpentine-like receptor PfSR25 is a monovalent cation sensor capable of modulating Ca2+ signaling in the parasites. Changing from high (140 mM) to low (5.4 mM) KCl concentration triggers [Ca2+]cyt increase in isolated parasites and this Ca2+ rise is blocked either by phospholipase C (PLC) inhibition or by depleting the parasite's internal Ca2+ pools. This response persists even in the absence of free extracellular Ca2+ and cannot be elicited by addition of Na+, Mg2+ or Ca2+. However, when the PfSR25 gene was deleted, no effect on [Ca2+]cyt was observed in response to changing KCl concentration in the knocked out (PfSR25 -) parasite. Finally, we also demonstrate that: i) PfSR25 plays a role in parasite volume regulation, as hyperosmotic stress induces a significant decrease in parasite volume in wild type (wt), but not in PfSR25 - parasites; ii) parasites lacking PfSR25 show decreased parasitemia and metacaspase gene expression on exposure to the nitric oxide donor sodium nitroprusside (SNP) and iii), compared to PfSR25 - parasites, wt parasites showed a better survival in albumax-deprived condition.

Neurologic complications in dengue virus infection: a prospective cohort study.

OBJECTIVE: This study aimed to evaluate the incidence and clinical spectrum of neurologic complications, predictors of central and peripheral nervous system involvement, and their outcome in patients with dengue virus infection (DENV). METHODS: To determine the extent of neurologic complications, we used a hospital-based prospective cohort study design, which included laboratory-confirmed cases of dengue and follow-up for 3 months. We also analyzed clinical and laboratory data to assess predictors of neurologic involvement. RESULTS: The study included enrollment of 486 cases. Two were lost to follow-up and excluded. Forty-five patients developed neurologic complications. Of these, 28 patients had CNS and 17 had peripheral nervous system (PNS) involvement, representing an incidence rate for neurologic complications of 9.26%. Significant predictors of CNS involvement were higher mean body temperature (p = 0.012), elevated hematocrit (p = 0.009), low platelet count (p = 0.021), and liver dysfunction (p < 0.001). Predictors of PNS involvement were higher mean body temperature (p = 0.031), rash (p = 0.002), and elevated hematocrit (p < 0.001). The mortality rate was 4.5%. The remainder of the patients recovered. CONCLUSION: An increasingly wide spectrum and higher incidence of neurologic complications of DENV are reported. Clinical and laboratory parameters such as higher mean body temperature, rash, increases in hematocrit, thrombocytopenia, and liver dysfunction are independent predictors of neurologic complications.

Perihematomal edema as predictor of outcome in spontaneous intracerebral hemorrhage.

BACKGROUND: Spontaneous intracerebral hemorrhage (SICH) is a form of cerebrovascular accident with a very high rate of morbidity and mortality. The determinants of prognosis include the demographic, clinical, laboratory, and radiologic factors. It is long known that the hematoma size has a negative impact on the outcome in SICH. The influence of perihematomal edema (PHE) is not established to the extent same as that of hematoma volume. Hence, we planned this study to determine as to what role does PHE plays in the outcome in SICH. AIM OF THE STUDY: To evaluate the prognostic influence of absolute and relative edema (ratio of absolute edema to hematoma volume) in the patients of SICH. MATERIALS AND METHODS: This is a prospective case-controlled study. A total of 44 patients were enrolled after excluding the confounding factors. The patients were evaluated and their disability was assessed using modified Rankin scale (MRS). The imaging was done in the interval between 24 and 72 h and the hematoma volume, absolute edema volume, and the relative edema were calculated. The outcome was reassessed at 12 weeks and defined as favorable if MRS < 3. RESULTS: A total of 69 patients were found to be having SICH on imaging; however, 25 patients were excluded as they had one of the criterion for exclusion. Hence, only 44 patients were included in the study. On univariate analysis, none of the demographic characteristics of the patients, vascular risk factors, presenting complaints, blood pressure, Glasgow coma scale, and MRS at admission, laboratory parameters were not significantly different in the two outcome groups. The hematoma volume was significantly higher in the poor outcome group (P < 0.0001) and the relative edema was associated with a favorable outcome at 12 weeks (P < 0.0001). On multivariate logistic regression, the hematoma volume and relative edema were found to have effect on the outcome similar to that seen on univariate analysis. CONCLUSION: In SICH, a larger hematoma volume is a predictor of poor outcome and a relative edema is associated with a better functional status.

Pregabalin in post traumatic neuropathic pain: Case studies.

Pregabalin is effective in the treatment of peripheral and central neuropathic pain. This study evaluated the effectiveness of pregablin in management of post traumatic peripheral nerve injury facial pain not responding to other medication like analgesics. Pregabalin was well tolerated. The most common adverse effects were dizziness and tiredness.