Cytoadherence by Plasmodium falciparum-infected erythrocytes is correlated with the expression of a family of variable proteins on infected erythrocytes

Plasmodium falciparum-infected erythrocytes (IRBCs) adhere specifically to venular endothelium and thereby evade spleen-dependent immune mechanisms. We have investigated the molecular basis of cytoadherence. We report here that the capacity for cytoadherence of IRBCs is correlated with the expression of a family of variable proteins on the surface of IRBCs. Essential to these studies was the use of in vitro techniques for modulating the cytoadherence phenotype of cloned parasites. In initial studies, we found culture-adapted parasites to be poorly cytoadherent or noncytoadherent. To select for cytoadherent parasites, we incubated knobbed IRBCs with C32 melanoma cells and cultured the adherent cells. Repeated rounds of selection produced parasites with increased cytoadherence. To select for noncytoadherent parasites, we cultured the cells that did not adhere to C32 melanoma cells. Cytoadherent IRBCs from two different cloned isolates had large (Mr greater than 2.4 x 10(5) radioiodinatable proteins that differed in size between the isolates but had in common the biochemical properties of trypsin sensitivity and insolubility with Triton X-100. The proteins were not detected with uninfected erythrocytes, indicating that they were parasite determined, nor were they detected with IRBCs containing parasites cultured for many months without selection. With continued selection for the cytoadherent phenotype, additional IRBC surface proteins with larger molecular sizes (Mr 2.9 x 10(5) and 3.2 x 10(5] appeared. A sequence of reversible changes in the cytoadherence phenotype of cloned parasites was accompanied by variation in the molecular size of the IRBC surface protein. Increased cytoadherence was correlated with expression of larger proteins and decreased cytoadherence was correlated with expression of smaller proteins; there was no change in the molecular size of two other parasite proteins associated with the IRBC membrane. The results indicate that the expression of this family of proteins is closely linked to the cytoadherence phenotype of the parasites, suggesting that the members of the protein family have a role in mediating cytoadherence between IRBCs and endothelial cells.

Development of the human retinal vasculature: cellular relations and VEGF expression

We have investigated the relationships of the cellular constituents of the retinal vasculature--astrocytes, microglia and pericytes--to the differentiating endothelium in human fetal retina. The vascular endothelium was stained using NADPH-diaphorase histochemistry in 12 human fetal retinae ranging in gestational age from 15-22 weeks. Specimens were double labeled using antibodies against glial fibrillary acid protein, alpha smooth muscle actin, or major histocompatibility complex class II antigens to label astrocytes, contractile cells and microglia, respectively. In addition, specimens of 12, 14, 16 and 20 weeks gestation were hybridized in situ for VEGF expression. In retinal wholemounts the vascularized area comprised four lobes that converged on the optic disc. The vascular network was more dense in the temporal lobes than in the nasal lobes, and different growth patterns were evident. Astrocytes were distributed in two layers--one associated with the optic axons and a deeper layer associated with the developing vessels. In retinae younger than 20 weeks, astrocytes in the deep layer were only loosely associated with the developing vessels and extended as far as 150 microns ahead of the most peripheral vessels. A closer register between retinal vessels and the distribution of astrocytes was evident in the nasal region of retinas older than 20 weeks. In situ hybridization demonstrated expression of VEGF mRNA in the vascular layer, superficial to the ganglion cell layer, at the margins of the vascularized zone. Differences were evident in the density of astrocyte coverage of developing vessels and in the extent of VEGF expression in different regions of the retina: the relationship of these differences to differentiation gradients in the neural retina is discussed. Intensely immunoreactive microglia were observed in the vascular layer, associated with the vascular endothelium as far as the most peripheral loops, but not beyond. Alpha smooth muscle actin-containing cells covered the proximal parts of large arteries, but not corresponding veins; they were absent from arterial side-arm branches, as well as the newly formed and small diameter vessels in the age range studies. The results suggest that microglia, contractile cells and astrocytes have distinct temporo-spatial relationships to the differentiating vascular endothelium in human retinas and that VEGF expression at the vascular front, presumably by astrocytes, is associated with the spread of the retinal vasculature, as described in other species.

The influence of air pollution on cardiovascular and pulmonary function and exercise capacity: Canadian Health Measures Survey (CHMS)

BACKGROUND

Air pollution has been associated with adverse cardiovascular effects.

OBJECTIVE

To measure the association between air pollution, spirometry, blood pressure, and exercise capacity.

METHODS

We used data from 5604 subjects collected during the Canada Health Measures Survey to test the association between air pollution measured on the day of the survey and spirometry (n=5011 subjects), blood pressure, and exercise capacity (n=3789 subjects).

RESULTS

An interquartile range (IQR) increase in ozone (17.0 ppb) was significantly associated with a 0.883% higher resting heart rate, a 0.718% higher systolic and 0.407% higher diastolic blood pressure, a 0.393% lower FEV1/FVC expressed as a percentage of predicted, and a 1.52% reduction in the aerobic fitness score (p<0.05). Resting systolic and diastolic blood pressure were approximately 0.5 mmHg higher for an (IQR 4.5 μg/m3) increase in PM2.5 (IQR 4.5 μg/m3) and 1 mmHg higher for a 12.6 ppb increase in NO2 (IQR 12.6 ppb). An increase in PM2.5 was also associated with an approximate 0.4% decrease in percent predicted FEV1 and FVC (p<0.05).

CONCLUSION

Exposure to higher concentrations of air pollution was associated with higher resting blood pressure and lower ventilatory function. Ozone was associated with reduced exercise capacity.

Quality-of-life following thoracotomy for lung cancer

Contrary to the issues of perioperative morbidity and survival following surgery for lung cancer, little attention has been given to quality-of-life. To address this, quality-of-life was assessed preoperatively and 1, 3, 6 and 9 months postoperatively in a cohort of 117 consecutive subjects who underwent thoracotomy with a certain or presumptive diagnosis of lung cancer. Those with cancer (n = 91) confirmed at thoracotomy were contrasted to those without (n = 26). Moderate to severe dyspnea, reported in 14% preoperatively, increased to 34% at 1 and 3 months (p < 0.005) but returned to approximately 10% at 6 and 9 months. Similarly, activities of daily living were impaired in 11% preoperatively; this disability increased to 21% at 1 month (p < 0.005), and returned to baseline at 6 and 9 months. Those with cancer compared to those without a postoperative diagnosis of cancer had similar quality-of-life preoperatively but deteriorated more in the postoperative period. This study demonstrates that important deterioration in quality-of-life occurs during the first 3 months postoperatively in those with a final diagnosis of cancer but improvement back to baseline can be expected thereafter.

Comparative effectiveness and safety of pharmacological and non-pharmacological interventions for insomnia: an overview of reviews

BACKGROUND

This review aimed to assess the existing evidence regarding the clinical effectiveness and safety of pharmacological and non-pharmacological interventions in adults with insomnia and identify where research or policy development is needed.

METHODS

MEDLINE, Embase, PsycINFO, The Cochrane Library, and PubMed were searched from inception until June 14, 2017, along with relevant gray literature sites. Two reviewers independently screened titles/abstracts and full-text articles, and a single reviewer with an independent verifier completed charting, data abstraction, and quality appraisal.

RESULTS

A total of 64 systematic reviews (35 with meta-analysis) were included after screening 5024 titles and abstracts and 525 full-text articles. Eight of the included reviews were rated as high quality using the Assessment of Multiple Systematic Reviews 2 (AMSTAR2) tool, and over half of the included articles (n = 40) were rated as low or critically low quality. Consistent evidence of effectiveness across multiple outcomes based on more than one high- or moderate quality review with meta-analysis was found for zolpidem, suvorexant, doxepin, melatonin, and cognitive behavioral therapy (CBT), and evidence of effectiveness across multiple outcomes based on one high-quality review with meta-analysis was found for temazepam, triazolam, zopiclone, trazodone, and behavioral interventions. These interventions were mostly evaluated in the short term (< 16 weeks), and there was very little harms data available for the pharmacological interventions making it difficult to evaluate their risk-benefit ratio.

CONCLUSIONS

Assuming non-pharmacological interventions are preferable from a safety perspective CBT can be considered an effective first-line therapy for adults with insomnia followed by other behavioral interventions. Short courses of pharmacological interventions can be supplements to CBT or behavioral therapy; however, no evidence regarding the appropriate duration of pharmacological therapy is available from these reviews.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42017072527.

Gene inactivation of Pf11-1 of Plasmodium falciparum by chromosome breakage and healing: identification of a gametocyte-specific protein with a potential role in gametogenesis

We report the identification of the product of the Plasmodium falciparum Pf11-1 gene and demonstrate that it is a gametocyte-specific protein that has a potential role in the rupture of the host erythrocyte and emergence of the gametes (gametogenesis). The Pf11-1 gene is a large locus (30 kb) whose sequence predicts a glutamic acid-rich polypeptide. Our identification of the Pf11-1 gene product as gametocyte specific was greatly facilitated by the isolation of a mutant parasite clone in which greater than 90% of the Pf11-1 gene was deleted. Molecular analysis of the mutant locus suggests that the underlying genetic mechanism is chromosome breakage and subsequent healing by the addition of telomere repeats. PCR-based analysis showed that similar DNA rearrangements occur commonly in small subpopulations of most laboratory strains, suggesting that the Pf11-1 locus represents a fragile chromosome region. Northern blot analysis demonstrates that a large Pf11-1 gene-specific transcript (much greater than 10 kb) is present in gametocytes but not in asexual blood stage parasites. The Pf11-1 protein was localized by electron microscopy to granules in the cytoplasm of gametocytes adjacent to the membrane of the parasitophorous vacuole. Following in vitro stimulation of gametogenesis, the Pf11-1 protein was found in the membrane of lysed erythrocytes, suggesting a role for Pf11-1 in erythrocyte rupture within the mosquito gut.

Reversed optokinetic nystagmus (OKN): mechanism and clinical significance

We studied reversed optokinetic nystagmus (OKN) in 31 patients and found that it is actually the patient's own gaze-modulated spontaneous nystagmus shifted to the primary position of gaze by optokinetic stimulation. Two of our 31 patients were known to have congenital nystagmus. Most of the 29 others were adults who presented with neurological symptoms and nystagmus and were therefore suspected of having posterior fossa lesions. However, their nystagmographic findings and benign natural history suggest that they also had congenital nystagmus, which was unrecognized until they developed incidental neurological symptoms. These cases support the view that reversed OKN is pathognomonic of a benign, probably congenital, nystagmus.

Promoting transplantation tolerance; adoptive regulatory T cell therapy

Transplantation is a successful treatment for end-stage organ failure. Despite improvements in short-term outcome, long-term survival remains suboptimal because of the morbidity and mortality associated with long-term use of immunosuppression. There is, therefore, a pressing need to devise protocols that induce tolerance in order to minimize or completely withdraw immunosuppression in transplant recipients. In this review we will discuss how regulatory T cells (T(regs)) came to be recognized as an attractive way to promote transplantation tolerance. We will summarize the preclinical data, supporting the importance of these cells in the induction and maintenance of immune tolerance and that provide the rationale for the isolation and expansion of these cells for cellular therapy. We will also describe the data from the first clinical trials, using T(regs) to inhibit graft-versus-host disease (GVHD) after haematopoietic stem cell transplantation and will address both the challenges and opportunities in human T(reg) cell therapy.

Voluntary hyperventilation in obesity hypoventilation

Arterial blood gas analysis was performed before and after 60 to 90 s of voluntary hyperventilation in 27 consecutive patients with occlusive sleep apnea syndrome (OSA) and daytime hypercapnia. The percentage of fall in PaCO2 from baseline was examined in relationship to age, body mass index, sleep-disordered breathing indices, and pulmonary function variables. In 14 subjects without airflow obstruction, only one individual could not voluntarily hyperventilate into the normal range, whereas 6 of 13 subjects with airflow obstruction could not hyperventilate to eucapnia. The average percentage of fall in PaCO2 was 16 mm Hg (SEM = 1.3 mm Hg). The percentage of fall in PaCO2 correlated significantly with FEV1/FVC ratio (r = 0.47, p = 0.01) and with FEV1 (r = 0.5, p = 0.008). Although the baseline PaCO2 did not correlate with FEV1, the posthyperventilation PaCO2 did (r = 0.54, p = 0.003). Voluntary hyperventilation studies herein suggest a predominant role for impairment of ventilatory control in the maintenance of hypercapnia in OSA since a fall of PaCO2 into the normal range can usually be obtained. The correlation between the percentage of fall in PaCO2 and spirometric measures of respiratory mechanics, as well as the inability of some subjects to normalize the PaCO2 voluntarily suggests an added role for respiratory mechanical impairment in obesity hypoventilation.

The efficacy and safety of the timolol/dorzolamide fixed combination vs latanoprost in exfoliation glaucoma

PURPOSE

To evaluate the safety and efficacy of the timolol/dorzolamide fixed combination vs latanoprost 0.005% in exfoliation glaucoma patients.

METHODS

We randomized in an observer-masked fashion 65 newly diagnosed exfoliation glaucoma patients to either the timolol/dorzolamide twice daily or latanoprost daily treatment for 2 months and then crossed these over to the other treatment.

RESULTS

A total of fifty-four patients completed the study. After 2 months of chronic dosing, the morning intraocular pressure (IOP) (10:00) was reduced from a baseline of 31.2+/-6.5 mmHg to 18.1+/-3.0 with the fixed combination and to 18.9+/-4.1 mmHg with latanoprost (P = 0.21). Six patients were discontinued early from both treatment periods owing to inadequate IOP control and two others were discontinued from latanoprost treatment only. The fixed combination showed a significantly greater incidence of taste perversion (P < 0.001) and stinging upon instillation (P = 0.036), while latanoprost showed a trend for increased conjunctival injection (P = 0.056). However, five patients demonstrated either bradycardia or asthmatic symptoms with initiation of the fixed combination therapy. One patient on latanoprost complained of dizziness. Patient preference was generally given to latanoprost (63 vs 20.3%) mainly because of its once daily dosing (P < 0001).

CONCLUSIONS

This study suggests that both latanoprost and the timolol/dorzolamide fixed combination are efficacious in the treatment of newly diagnosed exfoliation glaucoma.

Sleep patterns and problems in adolescents

A sleep questionnaire was administered to 390 students in an urban high school. Total sleep hours per week appeared to decrease between the ages of 12 and 18 years. In general, girls slept more than boys. The quality of sleep and the perception of sleep adequacy also decreased with age. Reporting of the occasional use of sleep medications and alcohol at bedtime was 4.6% and 10.5%, respectively. These findings suggest that sleep problems among adolescents represent normal physiologic processes as well as some serious disturbances that may reflect the social pressures prevalent during adolescence.

A study of head and eye movement in spasmus nutans

A case of spasmus nutans was studied using objective recordings of head and eye displacement in order to generate a precise description of the ocular oscillations and head nodding and to investigate their interrelationships. The ocularoscillations consisted of 11-Hz sinusoidal convergence movements. The head nodding consisted of a 3-Hz, 3 degrees peak to peak, sinusoidal oscillation in the horizontal plane. The occurrence of the nodding always abolished the ocular oscillation which was replaced by normal compensatory eye movements which assisted visual acuity. The hypothesis is made that the head nodding is not pathological; it is a learned behavioural pattern which permits the patient to nullify the pathological eye movements. In order to test this hypothesis further, objective evidence is required to determine the precise order of appearance of the abnormal head and eye movements in spasmus nutans.

Acute and chronic effects of continuous positive airway pressure therapy on left ventricular systolic and diastolic function in patients with obstructive sleep apnea and congestive heart failure

BACKGROUND

Obstructive sleep apnea (OSA) may contribute to the pathogenesis of congestive heart failure (CHF). Nocturnal continuous positive airway pressure (CPAP) therapy can alleviate OSA and may have a role in the treatment of CHF patients.

OBJECTIVES

To investigate the acute and chronic effects of CPAP therapy on left ventricular systolic function, diastolic function and filling pressures in CHF patients with OSA.

METHODS

Twelve patients with stable CHF (New York Heart Association II or III, radionuclide ejection fraction lower than 40%) underwent overnight polysomnography to detect OSA. In patients with OSA (n=7), echocardiography was performed at baseline (awake, before and during acute CPAP administration) and after 6.9+/-3.3 weeks of nocturnal CPAP therapy. Patients without OSA (n=5) did not receive CPAP therapy, but underwent a baseline and follow-up echocardiogram.

RESULTS

In CHF patients with OSA, acute CPAP administration resulted in a decrease in stroke volume (44+/-15 mL versus 50+/-14 mL, P=0.002) and left ventricular ejection fraction ([LVEF] 34.8+/-5.0% versus 38.4+/-3.3%, P=0.006) compared with baseline, but no change in diastolic function or filling pressures (peak early diastolic mitral annular velocity [Ea]: 6.0+/-1.6 cm/s versus 6.3+/-1.6 cm/s, P not significant; peak early filling velocity to peak late filling velocity [E/A] ratio: 1.05+/-0.74 versus 1.00+/-0.67, P not significant; E/Ea ratio: 10.9+/-4.1 versus 11.3+/-4.1, P not significant). In contrast, chronic CPAP therapy resulted in a trend to an increase in stroke volume (59+/-19 mL versus 50+/-14 mL, P=0.07) and a significant increase in LVEF (43.4+/-4.8% versus 38.4+/-3.3%, P=0.01) compared with baseline, but no change in diastolic function or filling pressures (Ea: 6.2+/-1.2 cm/s versus 6.3+/-1.6 cm/s, P not significant; E/A ratio: 1.13+/-0.61 versus 1.00+/-0.67, P not significant; E/Ea ratio: 12.1+/-2.7 versus 11.3+/-4.1, P not significant). There was no change in left ventricular systolic function, diastolic function or filling pressures at follow-up in CHF patients without OSA.

CONCLUSIONS

Acute CPAP administration decreased stroke volume and LVEF in stable CHF patients with OSA. In contrast, chronic CPAP therapy for seven weeks improved left ventricular systolic function, but did not affect diastolic function or filling pressures. The potential clinical implications of the discrepant effects of CPAP therapy on left ventricular systolic and diastolic function in CHF patients with OSA warrant further study.

A 60-kDa Plasmodium falciparum protein at the moving junction formed between merozoite and erythrocyte during invasion

Invasion of erythrocytes by malaria merozoites requires the formation of a junction of attachment between erythrocyte and merozoite membranes. The attachment junction initially forms at the apical region of the merozoite. It then moves around to the posterior of the merozoite as invasion proceeds. A monoclonal antibody against a 60-kDa merozoite protein (termed MCP-1 for merozoite capping protein 1) of Plasmodium falciparum reacts in an immunofluorescence pattern resembling the moving junction. By two-color immunofluorescence, MCP-1 was located at the attachment site formed between the merozoite apical region and erythrocyte. During invasion, MCP-1 separated and migrated around merozoites at the orifice of the parasitophorous vacuole. In newly-invaded erythrocytes, MCP-1 persisted at the pole of the young parasite nearest the erythrocyte membrane, suggesting its anterior-to-posterior movement. MCP-1 exhibited no variability in molecular mass among the FCR-3, Camp and 7G8 strains of P. falciparum, and the epitope was invariant in the P. falciparum strains studied. We conclude that MCP-1 may participate in merozoite invasion of erythrocytes by facilitating attachment or movement of the junction along the parasite cytoskeletal network.

Gaze failure, drifting eye movements, and centripetal nystagmus in cerebellar disease

Three abnormalities of eye movement in man are described which are indicative of cerebellar system disorder, namely, centripetally beating nystagmus, failure to maintain lateral gaze either in darkness or with eye closure, and slow drifting movements of the eyes in the absence of fixation. Similar eye movement signs follow cerebellectomy in the primate and the cat. These abnormalities of eye movement, together with other signs of cerebellar disease, such as rebound alternating, and gaze paretic nystagmus, are explained by the hypothesis that the cerebellum helps to maintain lateral gaze and that brain stem mechanisms which monitor gaze position generate compensatory biases in the absence of normal cerebellar function.

The mature erythrocyte surface antigen of Plasmodium falciparum is not required for knobs or cytoadherence

Intraerythrocytic Plasmodium falciparum parasites at the trophozoite and schizont stages synthesize a greater than 200-kDa protein, the mature erythrocyte surface antigen (MESA), that is localized at the membrane of infected red blood cells and manifests size polymorphism and antigenic diversity among parasite isolates. Because MESA is localized in the host cell membrane, we examined parasites with differing knob and cytoadherence phenotypes to determine whether MESA expression correlated with knob formation and cytoadherence. A cloned line of P. falciparum that was cultured with repeated selection for the knobbed and cytoadherent phenotypes did not express MESA, due to at least partial deletion of the single-copy MESA gene. In contrast, parasites from the same clone that were cultured without this selection lost the knobbed and cytoadherent phenotypes, but continued to express MESA. These results indicate that MESA is apparently not required for differentiation and multiplication of erythrocyte stage P. falciparum parasites in vitro, or for knob formation and cytoadherence. We speculate that MESA may have a role in evasion of the host immune response by P. falciparum.

An in vitro assay for sequestration: binding of Plasmodium falciparum-infected erythrocytes to formalin-fixed endothelial cells and amelanotic melanoma cells

Erythrocytes infected with Plasmodium falciparum bind specifically to cultured endothelial cells and to a line of amelanotic melanoma cells. We have fixed endothelial cells and amelanotic melanoma cells in various ways and determined whether the fixed cells were still able to bind infected erythrocytes. Only cells fixed with 1.0-2.5% formalin in phosphate-buffered saline continued to bind infected erythrocytes as well as unfixed cells. The mechanism of binding to fixed and unfixed cells appeared to be identical for the following reasons. First, erythrocytes infected by parasite strains that bound to unfixed cells also bound to fixed cells while those that did not bind to unfixed cells did not bind to fixed cells. Second, immune serum that inhibited binding to unfixed cells also inhibited binding to fixed cells. Third, electron microscopy showed that knobs were the points of attachment between infected erythrocytes and both fixed and unfixed melanoma cells. Fixed cells gave reproducible results over at least 2 months. Thus, we have developed a simplified, reproducible assay for measuring binding of P. falciparum-infected erythrocytes to target cells.

Internuclear ophthalmoplegia. An electro-oculographic study of peak angular saccadic velocities

Peak angular saccadic velocities were measured during 30 degrees saccades in 18 patients with internuclear ophthalmoplegia who had full or nearly full adduction range, and 25 normal subjects. The following observations were made: 1. In the normal group adduction velocities were significantly faster than abduction velocities and centring movements were faster than decentring movements. 2. In patients with internuclear ophthalmoplegia adduction movements were significantly slower than in normal subjects and were significantly slower than abduction velocities. 3. Abduction velocities in patients with internuclear ophthalmoplegia were significantly slower than abduction velocities in normal subjects. It was concluded that measurements of peak angular velocities during saccades may be useful in detecting internuclear ophthalmoplegia or confirming the presence of suspected internuclear ophthalmoplegia. Slow abduction suggests that many patients with internuclear ophthalmoplegia (60 per cent in this series) have lesions affecting the supranuclear pathways subserving horizontal conjugate gaze.

Assessment of ozone exposures in the greater metropolitan Toronto area

An ozone (O3) exposure assessment study was conducted in Toronto, Ontario, Canada during the winter and summer of 1992. A new passive O3 sampler developed by Harvard was used to measure indoor, outdoor, and personal O3 concentrations. Measurements were taken weekly and daily during the winter and summer, respectively. Indoor samples were collected at a total of 50 homes and workplaces of study participants. Outdoor O3 concentrations were measured both at home sites using the passive sampler and at 20 ambient monitoring sites with continuous monitors. Personal O3 measurements were collected from 123 participants, who also completed detailed time-activity diaries. A total of 2,274 O3 samples were collected. In addition, weekly air exchange rates of homes were measured.

The relationship between head and eye movement in congenital nystagmus with head shaking: objective recordings of a single case

Head shaking and congenital nystagmus were recorded in a patient presented with visual tasks. When she was at rest the nystagmus took a 6 cycles per second saw-tooth wave-form. When she was attentive the nystagmus beat at a 2 to 2.6 cycles per second with a saddle-shaped deformation which permitted foveation. The head shaking occurred occasionally when the patient was attentive and was phase-locked to the nystagmus with resemblances in wave form and direction. Deceleration of the head shaking to zero velocity and peak displacement (to the left) coincided with the onset of the saddle of the nystagmus and hence assisted foveation; all other parts of the head-shaking cycle were detrimental to vision. It is proposed that the head shaking has a common pathological origin with the nystagmus and that, just as an isolated congenital nystagmus wave form becomes altered with attention to permit periods of foveal fixation, the pattern of combined head and eye nodding in this patient provided similar peroids of fixation.