Neuregulin-1 attenuates hemolysis- and ischemia induced-cerebrovascular inflammation associated with sickle cell disease

OBJECTIVES

Individuals with sickle cell disease (SCD) are at severely heightened risk for cerebrovascular injury and acute cerebrovascular events, including ischemic and hemorrhagic stroke, potentially leading to impaired development and life-long physical and cognitive disabilities. Cerebrovascular injury specific to SCD includes inflammation caused by underlying conditions of chronic hemolysis and reduced cerebrovascular perfusion. The objectives of this study were to investigate whether expression of neuregulin-1β (NRG-1), an endogenous neuroprotective polypeptide, is increased in SCD or experimental conditions mimicking the hemolysis and ischemic conditions of SCD, and to determine if treatment with exogenous NRG-1 reduces markers of cerebrovascular inflammation.

MATERIALS AND METHODS

Plasma and brain-specific NRG-1 levels were measured in transgenic SCD mice. Endogenous NRG-1 levels and response to experimental conditions of excess heme and ischemia were measured in cultured human brain microvascular cells and astrocytes. Pre-treatment with NRG-1 was used to determine NRG-1's ability to ameliorate resultant cerebrovascular inflammation.

RESULTS

Plasma and brain-specific NRG-1 were elevated in transgenic SCD mice compared to healthy controls. Neuregulin-1 expression was significantly increased in cultured human microvascular cells and astrocytes exposed to excess heme and ischemia. Pre-treatment with NRG-1 reduced inflammatory chemokine (CXCL-1 and CXCL-10) and adhesion molecule (ICAM-1 and VCAM-1) expression and increased pro-angiogenic factors (VEGF-A) in microvascular cells and astrocytes exposed to excess heme and ischemia.

CONCLUSIONS

Elevated NRG-1 in SCD is likely a protective endogenous response to ongoing cerebrovascular insults caused by chronic hemolysis and reduced cerebrovascular perfusion. Administration of NRG-1 to reduce cerebrovascular inflammation may be therapeutically beneficial in SCD and warrants continued investigation.

Effects of Iron Supplements on Heme Scavengers in Pregnancy

In malaria endemic countries, anemia in pregnant women occurs as a result of erythrocyte destruction by Plasmodium infections and other causes including malnutrition. Iron supplementation is recommended as treatment of iron-deficiency anemia. Erythrocyte destruction results in increased release of cytotoxic free heme that is scavenged by haptoglobin (Hp), hemopexin (Hx) and heme oxygenase-1 (HO-1). Paradoxically, iron supplementation in pregnant women has been reported to enhance parasitemia and increase levels of free heme. The relationship between free heme, heme scavengers, and birth outcomes has not been investigated, especially in women who are on iron supplementation. We hypothesized that parasite-infected pregnant women on routine iron supplementation have elevated heme and altered expression of heme scavengers. A cross-sectional study was conducted to determine the association between plasma levels of free heme, HO-1, Hp, Hx, and malaria status in pregnant women who received routine iron supplementation and their birth outcomes. Heme was quantified by colorimetric assay and scavenger protein concentration by ELISA. We demonstrated that iron-supplemented women with asymptomatic parasitemia had increased free heme (mean 75.6 µM; interquartile range [IQR] 38.8–96.5) compared with nonmalaria iron-supplemented women (mean 34.9 µM; IQR 17.4–43.8, P < 0.0001). Women with preterm delivery had lower levels of Hx (mean 656.0 µg/mL; IQR 410.9–861.3) compared with women with full-term delivery (mean: 860.9 µg/mL; IQR 715.2–1055.8, P = 0.0388). Our results indicate that iron supplementation without assessment of circulating levels of free heme and heme scavengers may increase the risk for adverse pregnancy outcomes.

Elevated neuregulin-1β levels correlate with plasma biomarkers of cerebral injury and high stroke risk in children with sickle cell anemia

Stroke, or cerebral infarction, is one of the most serious complications of sickle cell anemia (SCA) in childhood, potentially leading to impaired development and life-long physical and cognitive disabilities. About one in ten children with SCA are at risk for developing overt stroke and an additional 25% may develop silent cerebral infarcts. This is largely due to underlying cerebral injury caused by chronic cerebral ischemia and vascular insult associated with SCA. We previously identified two elevated markers of cerebral injury, plasma brain-derived neurotropic factor (BDNF) and platelet-derived growth factor (PDGF)-AA, in children with SCA and high stroke risk. The objective of this study was to investigate whether neuregulin-1β (NRG-1), an endogenous neuroprotective polypeptide may also be elevated in children with SCA. Neuregulin-1β is involved in the preservation of blood brain barrier integrity and brain microvascular cell viability and is cytoprotective in conditions of heme-induced injury and ischemia. Since elevated plasma heme and ischemia are signature characteristics of SCA, we hypothesized that NRG-1 would be elevated in children with SCA, and that NRG-1 levels would also correlate with our biomarkers of cerebral injury. Plasma NRG-1, BDNF and PDGF-AA levels were measured in children with SCA and healthy Controls. Plasma NRG-1 was found to be nearly five-fold higher in those children with SCA compared to Controls. Neuregulin-1β was also positively correlated with both BDNF and PDGF-AA concentrations, but was not associated with degree of anemia, suggesting that NRG-1 production may be an endogenous response to subclinical cerebral ischemia in SCA warranting further exploration.

Mammography for symptomless women--not so wise?

For over 20 years, medical authorities have urged asymptomatic peri/postmenopausal women to undergo frequent mammography. In a recent paper, the authors tested whether early detection reduced the incidence of previously undetected late-stage cancer and saved lives. They compared data from 1976-1978 (pre- mammography) to 2006-2008 US data. Annualized age-adjusted cancer data per 100,000 women ≥ 40 years old showed that early-stage cancer detection cases increased, from 105 to 178 cases of localized disease and from seven to 56 cases of ductal carcinoma in situ; regional invasive late-stage cancer diminished slightly, from 85 to 78 cases; distant late-stage cancer showed no decline, with 17 cases in both 1976-1978 and 2006-2008; breast cancer mortality declined by 20 per 100,000 women, from 71 to 51 cases. Since mammogram detection produced no decline in late-stage distant cancer presentations (with high mortality rates), and an extremely modest reduction in invasive regional disease (with low mortality rates), improved treatment, not early detection, is the likely engine for the lives saved. Overdiagnosis--estimated at about 70,000 US women per year--inflicts terror, and triggers biopsies followed by unnecessary medical treatments that are painful, potentially harmful, may impair immune responsiveness and increase the risks for other cancers. Given the availability of annual clinical exams, routine mammography screening should now be seriously questioned.

Information-processing characteristics of explicit time estimation by patients with schizophrenia and normal controls

The information-processing characteristics of time estimation have not been well-documented. This research investigated explicit time estimation to test whether (1) it can occur "automatically" and (2) the cognitive function generally known as "working memory" predicts accuracy of time estimation. Data on two tasks requiring explicit time judgement (time interval estimation and production) are reported for a sample of 43 normal, healthy controls and 19 inpatients with chronic schizophrenia. Each task was given in a standard (passing time interval is unfilled) and dual-task format (interval is filled by oral reading). Multivariate analysis of variance suggested that for both patients' and the normal controls' time estimation accuracy was (1) highly sensitive to whether a passing interval was filled with a concurrent activity such as reading and (2) predictable on the basis of age, education, and working memory skills. Also, the effect of the dual-task manipulation did vary as a function of psychosis for the Time Interval Production task. The data suggest that procedures for explicit time judgements do not occur automatically and utilize controlled processes such as working memory.

Relations of early maternal employment and attachment in introvertive and extravertive adults

The present study examined attachment scores of adult children whose mothers were employed and how maternal employment varied as a function of children's personality styles. Children's extraversion was expected to moderate the effects of maternal employment on their attachment as adults. Responses of 106 undergraduates were obtained on 3 measures, the Eysenck Personality Inventory, the Adult Attachment Scale of Collins and Read, and the Adolescent Relationship Scales Questionnaire of Scharfe and Bartholomew. A median split was performed to divide subjects into those scoring High and Low on Extraversion. Subjects were then grouped on the basis of their mothers' employment status during the subjects' infancy (Full-time, Part-time, Non-employed). Subjects high on Extraversion seemed to show more adverse attachment consequences in adulthood following full-time maternal employment during infancy. Adults who scored high on extraversion may have been more comfortable with continual maternal presence during infancy, while those more introverted as adults may have adapted better to the periods of separation associated with infant day care.

Reactions to managed care among psychologists and social workers

Although the delivery system for mental health care is undergoing unprecedented changes with managed care, few empirical assessments of practitioners' responses exist. Directories of managed care providers were used to contact 139 providers of managed mental health care for an anonymous survey of experiences with case management and short-term therapy. The differential effects of managed care on the practices of doctoral-level psychologists, master's-level psychologists, and social workers were examined.

Performance on the Purdue pegboard and finger tapping by schizophrenics after mellow and frenetic antecedent music

Effects of musical selections on motor performance have been inconsistent. Using a 3-factor within-subjects design [mellow music (4:4 time), frenetic music (2:8 time), and white noise conditions], each of 34 schizophrenic inpatients volunteered to perform the Purdue Pegboard and Finger Oscillation (Tapping) following 1-min. counterbalanced presentations of three types of music. Both pegboard and tapping performance were higher after frenetic music but unaffected by mellow music.

Motor performance of schizophrenics after mellow and frenetic antecedent music

Previous research has yielded an inconclusive picture of the effects of music on motor performance. Using a 3-factor within-subjects design [mellow/4:4 time), frenetic/(2:8 time), and white noise music conditions], each of 19 schizophrenic inpatient volunteers performed a Purdue Pegboard and Finger Oscillation (Tapping) Test following 1-min. presentations of 3 types of music. Pegboard performance was higher after frenetic music but unaffected by mellow music; there was no effect on tapping.

Effects of mellow and frenetic music and stimulating and relaxing scents on walking by seniors

Previous research has yielded an inconclusive picture of the effects of music and scent on walking. Few laboratory studies have detected a beneficial effect of music; olfactory research has shown performance is positively affected for repetitive tasks but not yet on walking. The influence of these two types of stimuli in efficiency of exercise among seniors was assessed by measuring distance walked on an indoor course. Using a 3 x 3 factorial design [mellow music in 4:4 time, frenetic music in 2:8 time, and white noise by stimulating, relaxing, and control scent conditions], each of 20 volunteers from a senior center received nine randomized, 90-sec. exercise trials. Walking distance was reduced by mellow music but unaffected by stimulating music; there was no effect of scent.

Mellow and frenetic antecedent music during athletic performance of children, adults, and seniors

Previous research has yielded a contradictory picture of the effects of music on athletic performance. While athletes frequently report using music while training or during or before an event, laboratory studies have generally not detected a beneficial effect of music. The influence of music, judged mellow and frenetic, played before exercise was assessed by measuring stationary bicycle mileage. 60 volunteers from three age groups (child, adult, and senior) and with two levels of prior activity (high and low) were subjects. Each participant received three randomized 2-min. exercise trials, each preceded by 1-min. exposure to mellow music, frenetic music, or white noise. Mileage in both music conditions was significantly higher than that during the white-noise control trial except among the senior subjects. No significant differences between frenetic and mellow music were noted.

Effects of positive and negative music on performance of a karate drill

Although athletes frequently report using music while training or before an event, laboratory studies have not detected a beneficial effect, so the influence of positive and negative music on performance of a selected karate drill was investigated in this double-blind study using 14 volunteers from two Shotokan karate schools. Each subject performed a preselected drill three times following positive and negative music and white noise in a random order. Performance of the drill was rated on a 7-item, 5-point scale by 2 rates. Differences among conditions were assessed via a with-in-subject t test for paired scores. The subjects' self-evaluation of their performance was also examined. Enhancement of performance for both types of music over white noise was significant.