Ultrastructural characterization of host-parasite interactions of Plasmodium coatneyi in rhesus macaques.

Plasmodium coatneyi has been proposed as an animal model for human Plasmodium falciparum malaria as it appears to replicate many aspects of pathogenesis and clinical symptomology. As part of the ongoing evaluation of the rhesus macaque model of severe malaria, a detailed ultrastructural analysis of the interaction between the parasite and both the host erythrocytes and the microvasculature was undertaken. Tissue (brain, heart and kidney) from splenectomized rhesus macaques and blood from spleen-intact animals infected with P. coatneyi were examined by electron microscopy. In all three tissues, similar interactions (sequestration) between infected red blood cells (iRBC) and blood vessels were observed with evidence of rosette and auto-agglutinate formation. The iRBCs possessed caveolae similar to P. vivax and knob-like structures similar to P. falciparum. However, the knobs often appeared incompletely formed in the splenectomized animals in contrast to the intact knobs exhibited by spleen intact animals. Plasmodium coatneyi infection in the monkey replicates many of the ultrastructural features particularly associated with P. falciparum in humans and as such supports its use as a suitable animal model. However, the possible effect on host­parasite interactions and the pathogenesis of disease due to the use of splenectomized animals needs to be taken into consideration.

Guided self-help to manage binge eating in a dietetic-led community weight management service.

An estimated 30% of patients accessing community weight management services experience symptoms of binge eating disorder (BED). Guided self-help (GSH) is the recommended first line of treatment for BED. This study is a preliminary investigation into the effectiveness of GSH delivered by dietitians for patients with binge eating within a weight management service and a consideration of the association between wellbeing, therapeutic relationship and outcomes. The study was conducted as a single group, pre- and post-intervention study with 24 patients reporting symptoms of binge eating who completed the self-help manual with guidance from a trained community dietitian. Primary outcomes were eating disorder psychopathology and behaviours (Eating Disorder Evaluation Questionnaire), depression and anxiety. Principle results showed a significant reduction on all subscales of eating disorder psychopathology, anxiety and depression. There was a reduction in loss of control over eating but the 40% reduction in binge episodes was not statistically significant. Mid-treatment sessional ratings were positively associated with outcome. In conclusion, the GSH intervention was appropriate for dietitian delivery to patients with obesity and binge eating behaviour. This research indicates potential for other dietetic-led weight management services to deliver such interventions and support patients with binge eating accessing their service.

A Review of Plasmodium coatneyi-Macaque Models of Severe Malaria.

Malaria remains one of the most significant public health concerns in the world today. Approximately half the human population is at risk for infection, with children and pregnant women being most vulnerable. More than 90% of the total human malaria burden, which numbers in excess of 200 million annually, is due to Plasmodium falciparum. Lack of an effective vaccine and a dwindling stockpile of antimalarial drugs due to increased plasmodial resistance underscore the critical need for valid animal models. Plasmodium coatneyi was described in Southeast Asia 50 years ago. This plasmodium of nonhuman primates has been used sporadically as a model for severe malaria, as it mimics many of the pathophysiologic features of human disease. This review covers the reported macroscopic, microscopic, ultrastructural, and molecular pathology of P. coatneyi infection in macaques, specifically focusing on the rhesus macaque, as well as describing the critical needs still outstanding in the validation of this crucial model of human disease.

Differential patterns of endothelial and leucocyte activation in 'typhus-like' illnesses in Laos and Thailand.

Scrub typhus is responsible for a large proportion of undifferentiated fevers in south-east Asia. The cellular tropism and pathophysiology of the causative agent, Orientia tsutsugamushi, remain poorly understood. We measured endothelial and leucocyte activation by soluble cell adhesion molecule enzyme-linked immunosorbent assays in 242 Lao and Thai patients with scrub or murine typhus, leptospirosis, dengue, typhoid and uncomplicated falciparum malaria on admission to hospital. Soluble E-selectin (sE-selectin) levels were lowest in dengue, sL-selectin highest in scrub typhus with a high sE-selectin to sL-selectin ratio in leptospirosis patients. In scrub typhus patients elevated sL-selectin levels correlated with the duration of skin rash (P = 0.03) and the presence of eschar (P = 0.03), elevated white blood cell (WBC) count (P = 0.007), elevated lymphocyte (P = 0.007) and neutrophil counts (P = 0.015) and elevated levels of sE-selectin correlated with the duration of illness before admission (P = 0.03), the presence of lymphadenopathy (P = 0.033) and eschar (P = 0.03), elevated WBC (P = 0.005) and neutrophil counts (P = 0.0003). In comparison, soluble selectin levels in murine typhus patients correlated only with elevated WBC counts (P = 0.03 for sE-selectin and sL-selectin). Soluble intercellular adhesion molecule-1 and soluble vascular adhesion molecule-1 levels were not associated significantly with any clinical parameters in scrub or murine typhus patients. The data presented suggest mononuclear cell activation in scrub typhus. As adhesion molecules direct leucocyte migration and induce inflammatory and immune responses, this may represent O. tsutsugamushi tropism during early dissemination, or local immune activation within the eschar.

The VHL tumor suppressor inhibits expression of the IGF1R and its loss induces IGF1R upregulation in human clear cell renal carcinoma.

Clear cell renal cell cancer (CC-RCC) is a highly chemoresistant tumor characterized by frequent inactivation of the von Hippel-Lindau (VHL) gene. The prognosis is reportedly worse in patients whose tumors express immunoreactive type I insulin-like growth factor receptor (IGF1R), a key mediator of tumor cell survival. We aimed to investigate how IGF1R expression is regulated, and found that IGF1R protein levels were unaffected by hypoxia, but were higher in CC-RCC cells harboring mutant inactive VHL than in isogenic cells expressing wild-type (WT) VHL. IGF1R mRNA and promoter activities were significantly lower in CC-RCC cells expressing WT VHL, consistent with a transcriptional effect. In Sp1-null Drosophila Schneider cells, IGF1R promoter activity was dependent on exogenous Sp1, and was suppressed by full-length VHL protein (pVHL) but only partially by truncated VHL lacking the Sp1-binding motif. pVHL also reduced the stability of IGF1R mRNA via sequestration of HuR protein. Finally, IGF1R mRNA levels were significantly higher in CC-RCC biopsies than benign kidney, confirming the clinical relevance of these findings. Thus, we have identified a new hypoxia-independent role for VHL in suppressing IGF1R transcription and mRNA stability. VHL inactivation leads to IGF1R upregulation, contributing to renal tumorigenesis and potentially also to chemoresistance.

Cerebral calpain in fatal falciparum malaria.

Disruption of axonal transport may represent a final common pathway leading to neurological dysfunction in cerebral malaria (CM). Calpains are calcium (Ca2+)-activated cysteine proteases which have been implicated in axonal injury in neurological diseases of various aetiologies. In this study we examined the association between mu- and m-calpain, the specific inhibitor calpastatin, and axonal injury in post mortem brain tissue from patients who died from severe malaria. Calpains were associated with axons labelled for the beta-amyloid precursor protein that detects impaired axonal transport. Elevated levels of calpastatin were rarely observed in injured axons. There were increased numbers of neurones with mu-calpain in the nuclear compartment in severe malaria cases compared with non-neurological controls, and increased numbers of glia with nuclear mu-calpain in CM patients compared with non-CM malaria cases and non-neurological controls. There was marked redistribution of calpastatin in the sequestered Plasmodium falciparum-infected erythrocytes. Responses specific to malaria infection were ascertained following analysis of brain samples from fatal cases with acute axonal injury, HIV encephalitis, and progressive multifocal leucoencephalopathy. Our findings implicate a role for calpains in the modulation of disease progression in CM.

Neuropathological assessment of artemether-treated severe malaria.

In animals, high doses of intramuscular artemether and artemotil have been shown to cause an unusual pattern of selective damage to certain brainstem nuclei, especially those implicated in hearing and balance. We aimed to investigate whether a similar pattern arises in human adults. We examined the brainstems of adults who died after treatment with high dose artemether or quinine for severe falciparum malaria for evidence of a pattern of selective neuronal damage. Neuropathological findings were similar in recipients of quinine (n=15) and artemether (n=6; total artemether doses received 4-44 mg/kg). No evidence was recorded for artemether-induced neurotoxic effects.

Cellular stress and injury responses in the brains of adult Vietnamese patients with fatal Plasmodium falciparum malaria.

Immunohistochemical techniques have been used to investigate specific patterns of potentially reversible cellular injury, DNA damage, and apoptosis in the brainstems of Vietnamese patients who died of severe Plasmodium falciparum malaria. The degree and pattern of neuronal and glial stress responses were compared between patients with cerebral and non-cerebral malaria (CM), and appropriate non-malaria infected controls. The following markers were examined: (i) heat shock protein 70 (HSP70), for reversible injury; (ii) heme oxygenase-1, for oxidative stress; (iii & iv) two DNA-repair proteins, poly(ADP) ribose polymerase (PARP) and DNA-dependent protein kinase catalytic subunit; (v) poly(ADP) ribose, an end-product of PARP activity; and (vi) caspase-3-active, for apoptosis. Stress responses were found in a range of cell types as reflected by the widespread expression of HSP70. Oxidative stress predominated in the vicinity of vessels and haemorrhages. Some degree of DNA damage was found in the majority of malaria patients, but the distribution and frequency of the damage was much less than that observed in controls with irreversible neuronal injury. Similarly, caspase-3-active expression, as a measure of apoptosis, was no higher in the majority of malaria patients than the negative control cases, although 40% of CM cases expressed caspase-3-active in a small number of neurones of the pontine nuclei or within swollen axons of the pontocerebellar and corticospinal tracts. In conclusion, cells within the brainstem of all patients who died from severe malaria showed staining patterns indicative of considerable stress response and reversible neuronal injury. There was no evidence for a specific pattern of widespread irreversible cell damage in those patients with cerebral malaria.

Inducible nitric oxide synthase expression is increased in the brain in fatal cerebral malaria.

AIMS: Nitric oxide (NO) has been hypothesized to play a major role in the pathogenesis of cerebral malaria caused by P. falciparum infection. NO may act as a local neuroactive mediator contributing to the coma of cerebral malaria (CM). We hypothesized that increased expression of inducible nitric oxide synthase (iNOS) may cause increased release of NO, and examined the expression and distribution of iNOS in the brain during CM. MATERIAL AND RESULTS: Brain tissues from fatal cases of cerebral malaria in Thai adults were examined using immunohistochemical staining to detect iNOS. The distribution and strength of staining was compared between 14 patients with CM, three of whom were recovering from coma, and controls. iNOS expression was found in endothelial cells, neurones, astrocytes and microglial cells in CM cases. There was also strong staining in macrophages surrounding ring haemorrhages. iNOS staining was decreased in recovering malaria cases compared to acute CM, and was low in controls. Quantification showed a significant association between the intensity and number of iNOS positive vessels with the severity of malaria related histopathological changes, although the total number of cells staining was not increased compared to recovering CM cases. CONCLUSIONS: This study indicates that an acute induction of iNOS expression occurs in the brain during CM. This occurs in a number of different cells types, and is increased in the acute phase of CM compared to cases recovering from coma. As NO may activate a number of secondary neuropathological mechanisms in the brain, including modulators of synaptic function, induction of iNOS expression in cerebral malaria may contribute to coma, seizures and death.

Blood-brain barrier function in cerebral malaria and CNS infections in Vietnam.

BACKGROUND: The intraerythrocytic parasite Plasmodium falciparum induces the life-threatening neurologic syndrome of cerebral malaria (CM) from within cerebral blood vessels, without entering the brain parenchyma. OBJECTIVES: 1) To assess the use of CSF as an indicator of specific pathologic processes occurring in the brain during CM; 2) to compare this with other neurologic and infectious diseases to understand the distinct pathogenic features of CM; 3) to test the hypothesis that CM involves a specific functional breakdown of the blood-brain barrier (BBB). METHODS: 1) Radial immunodiffusion assays to detect albumin and IgG in matched plasma and CSF samples as indicators of BBB integrity and intrathecal IgG production; and 2) ELISA for soluble intracellular adhesion molecule-1 and sE-selectin, the cytokines tumor necrosis factor-alpha and transforming growth factor-beta1, and the matrix metalloproteinase MMP-9, to detect cellular activation and inflammatory responses within the brain. RESULTS: Albumin and IgG indices implied only minimal degree of BBB breakdown in a few cases of CM, with most remaining within the normal range. In contrast, cryptococcal, tubercular, and acute bacterial meningitis produced detectable changes in the composition of the CSF and evidence of BBB breakdown. CONCLUSIONS: CM appears to involve only subtle functional changes in BBB integrity with minimal intraparenchymal inflammatory responses compared with other neurologic infections. This focuses attention on local events within and around the cerebral microvasculature in CM, rather than indicating widespread parenchymal disease.

Differential binding of clonal variants of Plasmodium falciparum to allelic forms of intracellular adhesion molecule 1 determined by flow adhesion assay.

Adhesion of Plasmodium falciparum-infected erythrocytes to the endothelial ligand intercellular adhesion molecule 1 (ICAM-1) has been implicated in the pathogenesis of cerebral malaria. Recently, a high-frequency coding polymorphism in the N-terminal domain of ICAM-1 (ICAM-1(Kilifi)) that is associated with susceptibility to cerebral disease in Kenya has been described. Preliminary static adhesion assays suggested that two different selected P. falciparum lines, ITO4-A4 (A4) and ItG-ICAM (ItG), have different properties of binding to the natural variant proteins ICAM-1 and ICAM-1(Kilifi). Using a flow adhesion assay system, we have confirmed differences between the two lines in binding of parasitized erythrocytes to the variant ICAM-1 proteins. Total adhesion of ItG-infected erythrocytes to ICAM-1 and ICAM-1(Kilifi) is greater than that of A4-infected erythrocytes, and erythrocytes infected by both parasite strains show reduced binding to ICAM-1(Kilifi). However, under these physiologically relevant flow conditions, we have shown differences between A4 and ItG strains in dynamic rolling behavior on ICAM-1(Kilifi). The percentage of erythrocytes infected with A4 that roll on both ICAM-1 and ICAM-1(Kilifi) is greater than that of those infected with ItG. Also, the rolling velocity of A4-infected erythrocytes on ICAM-1(Kilifi) is markedly increased compared to that on ICAM-1, in contrast to the rolling velocity of ItG-infected erythrocytes, which is similar on both proteins. These findings suggest that different parasite lines can vary in their avidity for the same host ligand, which may have important consequences for the pathophysiology of P. falciparum malaria.

A quantitative analysis of the microvascular sequestration of malaria parasites in the human brain.

Microvascular sequestration was assessed in the brains of 50 Thai and Vietnamese patients who died from severe malaria (Plasmodium falciparum, 49; P. vivax, 1). Malaria parasites were sequestered in 46 cases; in 3 intravascular malaria pigment but no parasites were evident; and in the P. vivax case there was no sequestration. Cerebrovascular endothelial expression of the putative cytoadherence receptors ICAM-1, VCAM-1, E-selectin, and chondroitin sulfate and also HLA class II was increased. The median (range) ratio of cerebral to peripheral blood parasitemia was 40 (1.8 to 1500). Within the same brain different vessels had discrete but different populations of parasites, indicating that the adhesion characteristics of cerebrovascular endothelium change asynchronously during malaria and also that significant recirculation of parasitized erythrocytes following sequestration is unlikely. The median (range) ratio of schizonts to trophozoites (0.15:1; 0.0 to 11.7) was significantly lower than predicted from the parasite life cycle (P < 0.001). Antimalarial treatment arrests development at the trophozoite stages which remain sequestered in the brain. There were significantly more ring form parasites (age < 26 hours) in the cerebral microvasculature (median range: 19%; 0-90%) than expected from free mixing of these cells in the systemic circulation (median range ring parasitemia: 1.8%; 0-36.2%). All developmental stages of P. falciparum are sequestered in the brain in severe malaria.

Systemic endothelial activation occurs in both mild and severe malaria. Correlating dermal microvascular endothelial cell phenotype and soluble cell adhesion molecules with disease severity.

Fatal Plasmodium falciparum malaria is accompanied by systemic endothelial activation. To study endothelial activation directly during malaria and sepsis in vivo, the expression of cell adhesion molecules on dermal microvascular endothelium was examined in skin biopsies and correlated with plasma levels of soluble (circulating) ICAM-1, E-selectin, and VCAM-1 and the cytokine tumor necrosis factor (TNF)-alpha. Skin biopsies were obtained from 61 cases of severe malaria, 42 cases of uncomplicated malaria, 10 cases of severe systemic sepsis, and 17 uninfected controls. Systemic endothelial activation, represented by the up-regulation of inducible cell adhesion molecules (CAMs) on endothelium and increased levels of soluble CAMs (sCAMs), were seen in both severe and uncomplicated malaria and sepsis when compared with uninfected controls. Plasma levels of sICAM-1, sVCAM-1, and sE-selectin correlated positively with the severity of malaria whereas TNF-alpha was raised nonspecifically in malaria and sepsis. Immunohistochemical evidence of endothelial activation in skin biopsies did not correlate with sCAM levels or disease severity. This indicates a background of systemic endothelial activation, which occurs in both mild and severe malaria and sepsis. The levels of sCAMs in malaria are thus not an accurate reflection of endothelial cell expression of CAMs in a particular vascular bed, and other factors must influence their levels during disease.

Failure to block adhesion of Plasmodium falciparum-infected erythrocytes to ICAM-1 with soluble ICAM-1.

The adhesion of Plasmodium falciparum-infected erythrocytes is thought to play a central role in the pathogenesis of severe malaria. ICAM-1 has been identified as one of the host receptors for parasitized erythrocytes and has been implicated as being involved in progression to cerebral malaria. Thus, intervention strategies based on the reversal of this interaction could potentially be used to reduce morbidity and mortality. We have investigated the inhibition of the interaction between ICAM-1 and infected erythrocytes by using recombinant soluble ICAM-1 as competitor and find that we are unable to reduce adhesion to ICAM-1 in vitro.

Culturing Culex quinquefasciatus mosquitoes with a blood substitute diet for the females.

The tropical house mosquito Culex quinquefasciatus was cultured by feeding the females on an artificial diet, not on live animals or whole blood. This anautogenous strain has been maintained for more than fifty generations. The blood replacement diet for female mosquitoes, designed to simulate the tonicity and density of host blood, was based on ovalbumin, soya infant formula, globulins and adenosine triphosphate. Female adults of Cx quinquefasciatus were fed the artificial blood formula from "Parafilm' wax membrane-covered beakers. The diet was heated by radiant heat from a chamber containing an exothermic chemical reaction. This maintained the diet at a temperature of 33-37 degrees C for a period of up to 6 h, sufficient time to enable all the female mosquitoes to imbibe to satiation. After six generations on the artificial diet, female fecundity stabilized to a satisfactory level: the number of eggs per gonotrophic cycle averaged c. 85% of the "control' strain fed on whole blood from live anaesthetized guineapigs, i.e. 156 eggs per female from nine feeds on the artificial diet compared with 183 from six feeds of whole blood. Adult weight of Cx quinquefasciatus females was not significantly different, from generation 6 onwards, for strains fed on artificial diet or whole blood. Sex ratio and the rate of egg viability were also equivalent for the two strains.

The increased expression of adhesion molecules ICAM-3, E- and P-selectins on breast cancer endothelium.

Sequential interaction of neoplastic cells with the endothelium of tumour neovasculature is believed to be a significant step in tumour metastasis. Increasing evidence suggests that inducible endothelial adhesion molecules are intimately involved in this process. An immunohistochemical approach was used to examine the expression of adhesion molecules in 14 normal controls and a series of 64 invasive breast carcinomas. Endothelium in normal breast showed constitutive expression of PECAM (100 per cent), ICAM-2 (100 per cent), and P-selectin (64 per cent); variable and focal expression of ICAM-1 (71 per cent); and only weak staining for E-selectin (21 per cent). No ICAM-3 or VCAM-1 expression was observed. Similarly to normal breast endothelium, widespread and intense immunoreactivity on the endothelium of tumour-associated vessels was seen for PECAM (100 per cent), ICAM-1 (69 per cent), and ICAM-2 (95 per cent). In contrast to normal tissues, E- and P-selectins showed increased intensity of staining (52 and 67 per cent of cases, respectively) and expression of E- and P-selectins was more prominent at the tumour periphery. ICAM-3 expression was increased on tumour endothelium (15 per cent of cases), but in common with VCAM-1 (10 per cent) expression was focal. A previously unreported finding was the immunoreactivity of the neoplastic epithelial cells for the non-epithelial lineage markers ICAM-1 (34 per cent), ICAM-3 (10.9 per cent), PECAM (1.6 per cent), and E- and P-selectins (7 and 37 per cent of cases, respectively). These findings show that tumour endothelium displays significant heterogeneity and can assume a pro-inflammatory phenotype, probably as a result of cytokine stimulation. Upregulation of adhesion molecules might contribute to changes in invasive phenotype by promoting endothelial cell adhesion and angiogenesis, as well as forming a substratum for tumour cells to assemble and attract macrophages.