In vitro assembly of a prohead-like structure of the Rhodobacter capsulatus gene transfer agent

The gene transfer agent (GTA) is a phage-like particle capable of exchanging double-stranded DNA fragments between cells of the photosynthetic bacterium Rhodobacter capsulatus. Here we show that the major capsid protein of GTA, expressed in E. coli, can be assembled into prohead-like structures in the presence of calcium ions in vitro. Transmission electron microscopy (TEM) of uranyl acetate staining material and thin sections of glutaraldehyde-fixed material demonstrates that these associates have spherical structures with diameters in the range of 27-35 nm. The analysis of scanning TEM images revealed particles of mass approximately 4.3 MDa, representing 101+/-11 copies of the monomeric subunit. The establishment of this simple and rapid method to form prohead-like particles permits the GTA system to be used for genome manipulation within the photosynthetic bacterium, for specific targeted drug delivery, and for the construction of biologically based distributed autonomous sensors for environmental monitoring.     

Administration of pegylated recombinant human megakaryocyte growth and development factor to humans stimulates the production of functional platelets that show no evidence of in vivo activation

This report describes the effect of pegylated recombinant human megakaryocyte growth and development factor (PEG-rHuMGDF) on platelet production and platelet function in humans. Subjects with advanced solid tumors received PEG-rHuMGDF daily for up to 10 days. There was no increase in circulating platelet count at doses of 0.03 or 0.1 microgram/kg/d by day 12 of study. At doses of 0.3 and 1.0 microgram/kg/d there was a threefold median increase (maximum 10-fold) in platelet count by day 16. The platelets produced in vivo in response to PEG-rHuMGDF showed unchanged aggregation and adenosine triphosphate (ATP)-release responses in in vitro assays. Tests included aggregation and release of ATP in response to adenosine diphosphate (ADP) (10, 5, 2.5, and 1.25 mumol/L), collagen (2 micrograms/mL), thrombin-receptor agonist peptide (TRAP, 10 mumol/L) and ristocetin (1.5 mg/mL). Administration of aspirin to an individual with platelet count of 1,771 x 10(3)/L resulted in the typical aspirin-induced ablation of the normal aggregation and ATP-release response to stimulation with arachidonic acid (0.5 mg/mL), collagen, and ADP (2.5 and 1.25 mumol/L). There was no change in the expression of the platelet-surface activation marker CD62P (P-selectin) nor induction of the fibrinogen binding site on glycoprotein IIb/IIIa as reported by the monoclonal antibody, D3GP3. An elevation of reticulated platelets was evident after 3 days of treatment with PEG-rHuMGDF and preceded the increase in circulating platelet count by 5 to 8 days; this reflected the production of new platelets in response to PEG-rHuMGDF. At later time points, the mean platelet volume (MPV) decreased in a manner inversely proportional to the platelet count. Levels of plasma glycocalicin, a measure of platelet turnover, rose 3 days after the initial increase in the peripheral platelet count. The level of plasma glycocalicin was proportional to the total platelet mass, suggesting that platelets generated in response to PEG-rHuMGDF were not more actively destroyed. Thus, the administration of PEG-rHuMGDF, to humans, increased the circulating platelet count and resulted in fully functional platelets, which showed no detectable increase in reactivity nor alteration in activation status.     

Colorectal cancer incidence and screening in US Medicaid patients with and without HIV infection

Non-AIDS defining malignancies, particularly colorectal cancer (CRC), may be more prevalent among persons living with HIV (PLWH). Further, PLWH may be less likely to receive CRC screening (CRCS). We studied the epidemiology of CRC and CRCS patterns in PLWH and HIV-uninfected persons in a large US Medicaid population. We performed a matched cohort study examining CRC incidence in 2006 and CRCS between 1999 and 2007. Study participants were continuously enrolled in the Medicaid programs of California, Florida, New York, Ohio, and Pennsylvania. All PLWH enrollees were matched to five randomly sampled HIV-uninfected enrollees on 5-year age group, gender, and state. Adjusted odds ratios (AORs) for incident CRC (adjusted for comorbidity index) and the presence of CRCS (adjusted for comorbidity index and years in the data-set) among PLWH compared to HIV-uninfected enrollees were calculated. PLWH were not more likely to be diagnosed with CRC after adjusting for comorbidity index (unadjusted OR: 1.73, 95% confidence interval [CI]: 1.37–2.19; AOR 1.29; 95% CI: 0.98–1.70). While CRCS rates were low overall, PLWH were more likely to have received CRCS in unadjusted analyses (35.8% vs. 33.7%; OR 1.10, 95% CI: 1.07–1.13). This relationship was reversed after adjusting for comorbidity index and years in the data-set (AOR: 0.80, 95% CI: 0.77–0.83). Limitations of the study include a focus on the Medicaid population, an inability to detect fecal occult blood tests (FOBT), and having half of patients between 50 and 55 years of age. In conclusion, PLWH were not more likely to be diagnosed with CRC, but in adjusted analyses, were less likely to have received CRCS. As we showed a low rate of CRCS overall in this Medicaid population, researchers, clinicians, and policy-makers should improve access to and uptake of CRCS among all Medicaid patients, and particularly among PLWH.     

Envisioning an America Without Sexual Orientation Inequities in Adolescent Health

This article explicates a vision for social change throughout multiple levels of society necessary to eliminate sexual orientation health disparities in youths. We utilized the framework of Bronfenbrenner’s ecological theory of development, a multisystemic model of development that considers direct and indirect influences of multiple levels of the environment. Within this multisystem model we discuss societal and political influences, educational systems, neighborhoods and communities, romantic relationships, families, and individuals. We stress that continued change toward equity in the treatment of lesbian, gay, and bisexual youths across these levels will break down the barriers for these youths to achieve healthy development on par with their heterosexual peers.The articles that we have assembled in this special issue join a host of others documenting that lesbian, gay, and bisexual (LGB) adolescents experience health inequities that are driven by social determinants at multiple levels of influence.1–4 Rather than taking this further evidence as cause for increased pessimism, we share our vision for social change that we believe would create an America where LGB adolescents are given the same opportunity for healthy development as their heterosexual peers. We are not naive in believing that such change will come effortlessly or instantly, but we do believe in the value of sharing these aspirations as a way of illustrating the profound benefits they would engender.We begin by acknowledging that although transgender youths are not enumerated in the articles in this issue, health inequities have been described in a small number of studies with these youths.5,6 As Youth Risk Behavior Surveillance (YRBS) data do not assess gender identity, the focus of our discussion here is on LGB youths. We believe many of the social changes we articulate in this commentary would be of tremendous value to transgender youths, but at the same time recognize that they have additional needs that may not be sufficiently met by the changes we advocate here for their cisgendered LGB peers (e.g., medical care related to gender transitions). We also point out that sexual orientation is a multidimensional construct including sexual and romantic orientations, identity labels, and the gender of sexual partners7; our use of “LGB” is meant to be inclusive of the both- and same-sex oriented parts of these distributions. Among youths, these dimensions are correlated but not perfectly overlapping,8 and only recently have researchers begun to investigate how these multiple dimensions may be differentially related to health outcomes for LGB youths—a focus area of several of the articles in this special issue.As an organizational framework for considering the multilevel determinants of health disparities between LGB and heterosexual youths, we utilized Bronfenbrenner’s9 ecological theory of development. This theory describes a multisystemic model of development that nests youths within increasingly broad systems that act either directly or indirectly, by shaping the environment. This model has been applied widely in prevention research with youths10 and is consistent with the socioecological perspective espoused in the recent report of the Institute of Medicine (IOM) on the health of LGB and transgender (LGBT) people.11 At the broadest level, Bronfenbrenner describes the macrosystem, or the overarching structural or societal norms. These norms are described as “blueprints” that influence multiple aspects of the individual’s life and may be expressed at the ideological level or via written laws. The mesosystem includes the interrelations between the major settings in which the youths find themselves, and subsequently the impact of these interrelations upon the youths. Major settings in the mesosystem include local economy and work environment, government, religion, neighborhood, and mass media. The microsystem is composed of the relationships or contexts with which the child has direct contact, including romantic relationships, friendships and peer groups, and family relationships. Bronfenbrenner describes the relationships at this level as bidirectional (i.e., the child simultaneously has an influence on and is influenced by the individuals in his or her microsystem). Finally, the chronosystem reflects the effects of the passage of time, both for the individual and society at large. As it reflects the cumulative experiences a person has over the course of his or her lifetime, it is consistent with the life-course perspective articulated as 1 of the 4 guiding frameworks of the IOM report.11 The chronosystem also reflects sociohistorical changes, such as the passage of laws regarding same-sex marriage.Envisioning a future with thriving and healthy LGB youths will require change at all of these levels. Because of the dynamic interplay among these multiple levels, it is likely that changes at one level may alter determinants at other levels. For instance, institutional (e.g., discriminatory policies) and interpersonal (e.g., victimization) stressors engender maladaptive psychological responses (e.g., rumination, hypervigilance) that in turn predict negative mental health outcomes among LGB individuals.12,13 Thus, preventing social forms of stress would eliminate the need to change individual coping behaviors. However, it is also possible that change in some contexts may be profound, even if the improvements do not resonate to other levels. For example, having supportive and accepting parents promotes resilient development across a variety of adverse contexts. At the same time, our research14,15 and experience show that family support is not enough to overcome the deleterious effects of LGB-focused bullying and victimization. We cannot just seek to buffer LGB youths against victimization because resilience in the face of adversity is not the same thing as health equality. Teaching LGB youths how to cope and adapt to adversity should not be the goal of fair-minded people who want the best for all children. Rather we need to directly address determinants at multiple levels if we want true health equity. To explicate this vision, we begin by articulating change at the broadest macrosystem level and then honing down to individual factors.     

Odor memories regulate olfactory receptor expression in the sensory periphery

Odor learning induces structural and functional modifications throughout the olfactory system, but it is currently unknown whether this plasticity extends to the olfactory receptors (Or) in the sensory periphery. Here, we demonstrate that odor learning induces plasticity in olfactory receptor expression in the honeybee, Apis mellifera. Using quantitative RT‐PCR analysis, we show that six putative floral scent receptors were differentially expressed in the bee antennae depending on the scent environment that the bees experienced. Or151, which we characterized using an in vitro cell expression system as a broadly tuned receptor binding floral odorants such as linalool, and Or11, the specific receptor for the queen pheromone 9‐oxo‐decenoic acid, were significantly down‐regulated after honeybees were conditioned with the respective odorants in an olfactory learning paradigm. Electroantennogram recordings showed that the neural response of the antenna was similarly reduced after odor learning. Long‐term odor memory was essential for inducing these changes, suggesting that the molecular mechanisms involved in olfactory memory also regulate olfactory receptor expression. Our study demonstrates for the first time that olfactory receptor expression is experience‐dependent and modulated by scent conditioning, providing novel insight into how molecular regulation at the periphery contributes to plasticity in the olfactory system.     

Progesterone for the prevention of preterm birth in women with multiple pregnancies: the AMPHIA trial

Background

Adequate vitamin D concentrations during pregnancy are necessary to neonatal calcium homeostasis, bone maturation and mineralization. The aim of study is to evaluate serum vitamin D concentrations in mothers and their newborns and effect of vitamin D deficiency on pregnancy outcomes.

Methods

552 pregnant women were recruited from Tehran University educating hospitals in the winter of 2002. Maternal and cord blood samples were taken at delivery. The serum was assayed for 25-hydroxyvitamin D3, calcium, phosphorus and parathyroid hormone.

Results

The prevalence of vitamin D deficiency in maternal and cord blood samples were 66.8% and 93.3%, respectively (<35 nmol/l). There was significant correlation between maternal and cord blood serum concentrations of vitamin D. In mothers with vitamin D deficiency, cord blood vitamin D concentrations was lower than those from normal mothers (P = .001). Also, a significant direct correlation was seen between maternal vitamin D intake and weight gain during pregnancy.

Conclusion

Consideration to adequate calcium and vitamin D intake during pregnancy is essential. Furthermore, we think it is necessary to reconsider the recommendation for vitamin D supplementation for women during pregnancy.     

Test–retest repeatability of [18F]Flortaucipir PET in Alzheimer’s disease and cognitively normal individuals

The aim of this study was to investigate the test–retest (TRT) repeatability of various parametric quantification methods for [¹⁸F]Flortaucipir positron emission tomography (PET). We included eight subjects with dementia or mild cognitive impairment due to Alzheimer’s disease and six cognitively normal subjects. All underwent two 130-min dynamic [¹⁸F]Flortaucipir PET scans within 3 ± 1 weeks. Data were analyzed using reference region models receptor parametric mapping (RPM), simplified reference tissue method 2 (SRTM2) and reference logan (RLogan), as well as standardized uptake value ratios (SUVr, time intervals 40–60, 80–100 and 110–130 min post-injection) with cerebellar gray matter as reference region. We obtained distribution volume ratio or SUVr, first for all brain regions and then in three tau-specific regions-of-interest (ROIs). TRT repeatability (%) was defined as |retest–test|/(average (test + retest)) × 100. For all methods and across ROIs, TRT repeatability ranged from (median (IQR)) 0.84% (0.68–2.15) to 6.84% (2.99–11.50). TRT repeatability was good for all reference methods used, although semi-quantitative models (i.e. SUVr) performed marginally worse than quantitative models, for instance TRT repeatability of RPM: 1.98% (0.78–3.58) vs. SUVr_80–100: 3.05% (1.28–5.52), p < 0.001. Furthermore, for SUVr_80–100 and SUVr_110–130, with higher average SUVr, more variation was observed. In conclusion, while TRT repeatability was good for all models used, quantitative methods performed slightly better than semi-quantitative methods.