Search

Gestational hypertension, often associated with elevated soluble Fms-related receptor tyrosine kinase 1 (sFlt-1), poses significant risks to both maternal and fetal health. Hydrogen sulfide (H2S), a gasotransmitter, has demonstrated blood pressure-lowering effects in hypertensive animals and humans. However, its role in pregnancy-induced hypertension remains unclear. This study investigated the impact of GYY4137, a slow-release H2S donor, on sFlt-1-induced hypertension in pregnant rats . Pregnant rats were administered sFlt-1 (6 μg/kg/day, intravenously) or vehicle from gestation day (GD) 12-20. A subset of these groups received GYY4137 ( 50 mg/kg/day, intraperitoneal) from GD 16-20. Serum H2S levels, mean arterial blood pressure, uterine artery blood flow, and vascular reactivity were assessed. Elevated sFlt-1 reduced both maternal weight gain and serum H2S levels. GYY4137 treatment restored both weight gain and H2S levels in sFlt-1 dams. sFlt-1 increased mean arterial pressure and decreased uterine artery blood flow in pregnant rats. However, treatment with GYY4137 normalized blood pressure and restored uterine blood flow in sFlt-1 dams. sFlt-1 dams exhibited heightened vasoconstriction to phenylephrine and GYY4137 significantly mitigated the exaggerated vascular contraction. Notably, sFlt-1 impaired endothelium-dependent relaxation, while GYY4137 attenuated this impairment by upregulating eNOS protein levels and enhancing vasorelaxation in uterine arteries. GYY4137 mitigated sFlt-1-induced fetal growth restriction. In conclusion, sFlt-1 mediated hypertension is associated with decreased H2S levels. Replenishing H2S with the donor GYY4137 mitigates hypertension and improves vascular function and fetal growth outcomes. This suggests modulation of H2S could offer a novel therapeutic strategy for managing gestational hypertension and adverse fetal effects.

Alternative silvicultural systems to clearfelling are being adopted in Great Britain as a means of increasing the species and structural diversity of conifer plantation forests. One area where knowledge is lacking is the critical level of below-canopy light for survival and growth of young seedlings. This was investigated by planting seedlings of European larch Larix decidua (Mill.), Scots pine Pinus sylvestris L., Sitka spruce Picea sitchensis (Bong.(Carr.)), Douglas fir Pseudotsuga menziesii (Mirb.(Franco.)), and western hemlock Tsuga heterophylla (Raf. (Sarg.)) in a Sitka spruce plantation thinned to 3 different spacings. The incident light intensity beneath the canopy ranged from about 2 to over 60 per cent of full light. Planting in an adjoining open area provided an indication of growth under full light. Growth and survival of these seedlings were followed for 4 growing seasons. The highest seedling survival was found under the widest spacing and declined with closer spacing and lower light intensity. Only Douglas fir and western hemlock seedlings survived at the closest spacing, and in low percentages. The tallest seedlings of each species were found in the open grown conditions but survival was variable due to increased weed competition. Species-specific growth responses showed little difference under high light conditions but performance at low light was generally consistent with shade tolerance rankings in the literature except that Sitka spruce shade tolerance was slightly lower than expected. Minimum light requirements for these species increased from 10 to 30 per cent of full light with decreasing shade tolerance. Other studies of incident light in Sitka spruce plantations indicated that target basal areas in the range 25â30 m2 haâ1 are required if these light conditions are to be met, which suggests an irregular shelterwood system with frequent interventions should be favoured.

WT1 encodes a podocyte transcription factor whose variants can cause an untreatable glomerular disease in early childhood. Although WT1 regulates many podocyte genes, it is poorly understood which of them are initiators in disease and how they subsequently influence other cell‐types in the glomerulus. We hypothesised that this could be resolved using single‐cell RNA sequencing (scRNA‐seq) and ligand‐receptor analysis to profile glomerular cell–cell communication during the early stages of disease in mice harbouring an orthologous human mutation in WT1 (Wt1R394W/+). Podocytes were the most dysregulated cell‐type in the early stages of Wt1R394W/+ disease, with disrupted angiogenic signalling between podocytes and the endothelium, including the significant downregulation of transcripts for the vascular factors Vegfa and Nrp1. These signalling changes preceded glomerular endothelial cell loss in advancing disease, a feature also observed in biopsy samples from human WT1 glomerulopathies. Addition of conditioned medium from murine Wt1R394W/+ primary podocytes to wild‐type glomerular endothelial cells resulted in impaired endothelial looping and reduced vascular complexity. Despite the loss of key angiogenic molecules in Wt1R394W/+ podocytes, the pro‐vascular molecule adrenomedullin was upregulated in Wt1R394W/+ podocytes and plasma and its further administration was able to rescue the impaired looping observed when glomerular endothelium was exposed to Wt1R394W/+ podocyte medium. In comparative analyses, adrenomedullin upregulation was part of a common injury signature across multiple murine and human glomerular disease datasets, whilst other gene changes were unique to WT1 disease. Collectively, our study describes a novel role for altered angiogenic signalling in the initiation of WT1 glomerulopathy. We also identify adrenomedullin as a proangiogenic factor, which despite being upregulated in early injury, offers an insufficient protective response due to the wider milieu of dampened vascular signalling that results in endothelial cell loss in later disease. © 2024 The Author(s). The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland. [ABSTRACT FROM AUTHOR]

Understanding the neurobiology of social bonding in non-human primates is a critical step in understanding the evolution of monogamy, as well as understanding the neural substrates for emotion and behavior. Coppery titi monkeys (Callicebus cupreus) form strong pair bonds, characterized by selective preference for their pair mate, mate-guarding, physiological and behavioral agitation upon separation, and social buffering. Mate-guarding, or the "maintenance" phase of pair bonding, is relatively under-studied in primates. In the current study, we used functional imaging to examine how male titi monkeys viewing their pair mate in close proximity to a stranger male would change regional cerebral glucose metabolism. We predicted that this situation would challenge the pair bond and induce "jealousy" in the males. Animals were injected with [18F]-fluorodeoxyglucose (FDG), returned to their cage for 30 min of conscious uptake, placed under anesthesia, and then scanned for 1 hour on a microPET P4 scanner. During the FDG uptake, males (n=8) had a view of either their female pair mate next to a stranger male ("jealousy" condition) or a stranger female next to a stranger male (control condition). Blood and cerebrospinal fluid samples were collected and assayed for testosterone, cortisol, oxytocin, and vasopressin. Positron emission tomography (PET) was co-registered with structural magnetic resonance imaging (MRI), and region of interest analysis was carried out. Bayesian multivariate multilevel analyses found that the right lateral septum (Pr(b>0)=93%), left posterior cingulate cortex (Pr(b>0)=99%), and left anterior cingulate (Pr(b>0)=96%) showed higher FDG uptake in the jealousy condition compared to the control condition, while the right medial amygdala (Pr(b>0)=85%) showed lower FDG uptake. Plasma testosterone and cortisol concentrations were higher during the jealousy condition. During the jealousy condition, duration of time spent looking across at the pair mate next to a stranger male was associated with higher plasma cortisol concentrations. The lateral septum has been shown to be involved in mate-guarding and mating-induced aggression in monogamous rodents, while the cingulate cortex has been linked to territoriality. These neural and physiological changes may underpin the emotion of jealousy, which can act in a monogamous species to preserve the long-term integrity of the pair.

Social bonds, especially attachment relationships, are crucial to our health and happiness. However, what we know about the neural substrates of these bonds is almost exclusively limited to rodent models and correlational experiments in humans. Here, we used socially monogamous non-human primates, titi monkeys (Callicebus cupreus) to experimentally examine changes in regional and global cerebral glucose metabolism (GCGM) during the formation and maintenance of pair bonds. Baseline positron emission tomography (PET) scans were taken of thirteen unpaired male titi monkeys. Seven males were then experimentally paired with females, scanned and compared, after one week, to six age-matched control males. Five of the six control males were then also paired and scanned after one week. Scans were repeated on all males after four months of pairing. PET scans were coregistered with structural magnetic resonance imaging (MRI), and region of interest (ROI) analysis was carried out. A primary finding was that paired males showed a significant increase in [18F]-fluorodeoxyglucose (FDG) uptake in whole brain following one week of pairing, which is maintained out to four months. Dopaminergic, motivational areas and those involved in social behavior showed the greatest change in glucose uptake. In contrast, control areas changed only marginally more than GCGM. These findings confirm the large effects of social bonds on GCGM. They also suggest that more studies should examine how social manipulations affect whole-brain FDG uptake, as opposed to assuming that it does not change across condition.

Pair bonding leads to increases in dopamine D1 receptor (D1R) binding in the nucleus accumbens of monogamous prairie voles. In the current study, we hypothesized that there is similar up-regulation of D1R in a monogamous primate, the titi monkey (Callicebus cupreus). Receptor binding of the D1R antagonist [11 C]-SCH23390 was measured in male titi monkeys using PET scans before and after pairing with a female. We found that within-subject analyses of pairing show significant increases in D1R binding in the lateral septum, but not the nucleus accumbens, caudate, putamen, or ventral pallidum. The lateral septum is involved in a number of processes that may contribute to social behavior, including motivation, affect, reward, and reinforcement. This region also plays a role in pair bonding and paternal behavior in voles. Our observations of changes in D1R in the lateral septum, but not the nucleus accumbens, suggest that there may be broadly similar dopaminergic mechanisms underlying pair bonding across mammalian species, but that the specific changes to neural circuitry differ. This study is the first research to demonstrate neuroplasticity of the dopamine system following pair bonding in a non-human primate; however, substantial variability in the response to pairing suggests the utility of further research on the topic.

Social monogamy at its most basic is a group structure in which two adults form a unit and share a territory. However, many socially monogamous pairs display attachment relationships known as pair bonds, in which there is a mutual preference for the partner and distress upon separation. The neural and hormonal basis of this response to separation from the adult pair mate is under-studied. In this project, we examined this response in male titi monkeys (Callicebus cupreus), a socially monogamous New World primate. Males underwent a baseline scan, a short separation (48 h), a long separation (approximately 2 weeks), a reunion with the female pair mate and an encounter with a female stranger (with nine males completing all five conditions). Regional cerebral glucose metabolism was measured via positron emission tomography (PET) imaging using [18F]-fluorodeoxyglucose (FDG) co-registered with structural magnetic resonance imaging (MRI), and region of interest (ROI) analysis was carried out. In addition, plasma was collected and assayed for cortisol, oxytocin (OT), vasopressin (AVP), glucose and insulin concentrations. Cerebrospinal fluid (CSF) was collected and assayed for OT and AVP. We used generalized estimating equations (GEE) to examine significant changes from baseline. Short separations were characterized by decreases in FDG uptake, in comparison to baseline, in the lateral septum (LS), ventral pallidum (VP), paraventricular nucleus of the hypothalamus (PVN), periaqueductal gray (PAG), and cerebellum, as well as increases in CSF OT, and plasma cortisol and insulin. Long separations differed from baseline in reduced FDG uptake in the central amygdala (CeA), reduced whole brain FDG uptake, increased CSF OT and increased plasma insulin. The response on encounter with a stranger female depended on whether or not the male had previously reproduced with his pair mate, suggesting that transitions to fatherhood contribute to the neurobiology underlying response to a novel female. Reunion with the partner appeared to stimulate coordinated release of central and peripheral OT. The observed changes suggest the involvement of OT and AVP systems, as well as limbic and striatal areas, during separation and reunion from the pair mate.

Background: Beta‐2 transferrin (B2‐Tf) gel electrophoresis (GE) is the preferred non‐invasive diagnostic modality for confirming cerebrospinal fluid (CSF) in body fluids. While B2‐Tf GE testing is highly sensitive and specific for CSF, false‐positive (FP) and false‐negative (FN) results can lead to diagnostic and therapeutic dilemmas. Several series have demonstrated potential causes of false B2‐Tf GE results, but few studies have reported reasons for these errors. The purpose of this systematic review was to describe sources of B2‐Tf GE errors. Methods: A systematic review was performed by searching OVID, EMBASE, and Web of Science databases for B2‐Tf GE studies. After applying exclusion criteria, original research studies directly addressing erroneous B2‐Tf GE results underwent qualitative analysis. Results: Of the 243 abstracts screened, 71 underwent full‐text review and 18 studies reporting B2‐Tf GE errors were included for analysis. There were 15 potential FPs, 12 actual FPs, 12 potential FNs, 19 actual FNs, and 14 indeterminate results. There were also 246 potentially indeterminate results from in vitro studies. Reasons for B2‐Tf GE errors included serum transferrin alterations (n = 17; all potential), infection related (n = 13; 9 potential), orbital or salivary contamination (n = 2; 1 potential), and collection related (n = 255; 246 potential). There were 31 false or indeterminate results with unspecified reasons. There were no reported errors due to laboratory processing. Conclusions: Multiple potential or actual reasons for false or indeterminate results have been reported for B2‐Tf GE testing of rhinorrhea and otorrhea. Future studies should explore reasons for B2‐Tf testing errors and how these may affect clinical decision making. [ABSTRACT FROM AUTHOR]

The cause of warming in the Southern Hemisphere during the most recent deglaciation remains a matter of debate. Hypotheses for a Northern Hemisphere trigger, through oceanic redistributions of heat, are based in part on the abrupt onset of warming seen in East Antarctic ice cores and dated to 18,000 years ago, which is several thousand years after high-latitude Northern Hemisphere summer insolation intensity began increasing from its minimum, approximately 24,000 years ago. An alternative explanation is that local solar insolation changes cause the Southern Hemisphere to warm independently. Here we present results from a new, annually resolved ice-core record from West Antarctica that reconciles these two views. The records show that 18,000 years ago snow accumulation in West Antarctica began increasing, coincident with increasing carbon dioxide concentrations, warming in East Antarctica and cooling in the Northern Hemisphere associated with an abrupt decrease in Atlantic meridional overturning circulation. However, significant warming in West Antarctica began at least 2,000 years earlier. Circum-Antarctic sea-ice decline, driven by increasing local insolation, is the likely cause of this warming. The marine-influenced West Antarctic records suggest a more active role for the Southern Ocean in the onset of deglaciation than is inferred from ice cores in the East Antarctic interior, which are largely isolated from sea-ice changes.

Titi monkeys (Callicebus cupreus) are a monogamous, New World primate. Adult pair-mates form a bidirectional social bond and offspring form a selective unidirectional bond to their father. Some of the neurobiology involved in social bonds and maternal behavior is similar to the neural circuitry involved in nonsocial reward. Due to these overlapping mechanisms, social states may affect responses to external rewarding stimuli. We sought to determine whether having a social attachment, and/or being in the presence of that attachment figure, can affect an individual's response to a rewarding stimulus. In addition, we compared affiliative bonds between pair-mates to those between offspring and fathers. Eighteen adult male titi monkeys were either living alone (Lone), with a female pair-mate (Paired), or with the natal group (Natal; N = 6/condition). Each individual went through eight 30-min preference tests for a sweet substance, Tang. For Paired and Natal males, half of the test sessions were with their attachment figure and half were alone. Lone males were always tested alone. Preference scores for Tang, time spent drinking, affiliative, and arousal behaviors were measured. Paired and Natal males emitted significantly more isolation peeps and locomoted more when tested alone compared to when tested with their attachment figure, and paired males engaged in more affiliative behavior than Natal males. Lone males engaged in significantly more behaviors indicative of behavioral arousal such as locomotion and piloerection compared to Paired and Natal males. Finally, Paired males drank significantly more Tang and had a significantly greater preference for Tang compared to Lone and Natal males. These results indicate that offspring undergo a behavioral separation response upon separation from their father that persists into adulthood, Lone males are more behaviorally reactive, and that living with an attachment figure and the type of attachment relationship result in different responses to a rewarding sweet stimulus.

Medial temporal lobe brain structures, such as the amygdala, play an important role in the normal perception and generation of emotional behavior. Little research, however, has assessed the role of such structures across the neurodevelopmental trajectory. We assessed emotional behavioral responses of rhesus macaques that received bilateral ibotenic acid lesions of the amygdala or hippocampus at 2 weeks of age and sham-operated controls. At 9 and 18 months of age, animals interacted with novel objects that varied in visual complexity as a means of varying emotional salience. All animals behaved differently in the presence of visually simple, as compared to complex, objects, suggesting that they were sensitive to variation in emotional salience. Across both experiments, amygdala-lesioned animals appeared to be less behaviorally inhibited insofar as they explored all objects most readily. Interestingly, hippocampus-lesioned animals' propensity for exploration mirrored that of control animals in some contexts but that of amygdala-lesioned animals in other contexts. At 18 months of age, both amygdala-lesioned and hippocampus-lesioned animals were judged to be less fearful than controls during the testing procedure. Implications for understanding the neurobiology of emotional behavior are discussed.

Understanding how mathematics is taught in the classroom is an important first step in connecting mathematics instruction to student learning. This study sheds light on mathematics teaching in kindergarten and first grade—the grades at which initial understandings, as well as obstacles to later progress, begin to emerge. Using the Early Childhood Longitudinal Study Kindergarten Class of 1998-99 (ECLS-K) survey, we consider (i) how much time teachers spend on mathematics on days when they teach this subject, (ii) the content of mathematics instruction, and (iii) the pedagogical techniques used. We find that time spent on mathematics instruction, content coverage, and pedagogical techniques varies between teachers as a function of school location and type, classroom composition, and a range of teacher attributes that includes demographics, preparation, level of effort, and professional development activities.

Study Objectives: Insomnia is influenced by psychosocial and environment factors. This study aims to examine the differential of insomnia symptoms between rural-to-urban migrants and non-migrants in China. Design: A cross-sectional study. Setting: Ten townships throughout China. Patients or Participants: One hundred and ninety-seven Chinese adults aged 18 to 64 years, with an oversample of migrants. Measurements and Results: Professional interviewers and community doctors used a questionnaire to collect information on migration, insomnia symptoms, and other variables. Multivariable binomial logistic regression models were used to examine the relations between migration status and presence of at least one insomnia symptom, while adjusting for age, sex, education, income, number of chronic medical conditions, depression, and other covariates. The numbers of permanent urban residents, rural non-migrants, and rural-to-urban migrants in the study were 93 (47%), 47 (24%), and 57 (29%), respectively. The probability of reporting at least one of the five insomnia symptoms measured was 40% for permanent urban residents, 62% for rural non-migrants, and 68% for migrants (P = 0.001). Using permanent urban residents as the reference group, the multiply-adjusted odd ratios of having at least one insomnia symptom were 3.00 (95% CI: 1.36 – 6.62) for migrants and 1.86 (95% CI: 0.73 – 4.74) for rural non-migrants. The adjusted odd ratio for insomnia symptoms predicted from each additional chronic medical condition was 1.71 (95% CI: 1.13 – 2.60). 2 Conclusions: Compared to permanent urban residents, rural-to-urban migrants in China have higher prevalence of insomnia symptoms. The number of chronic medical conditions reported is also independently related to sleep disturbance. Key words: migration status, insomnia, China

The neurobiology of social bonding, despite its relevance to human mental health, has been studied primarily in rodents. In this study we used position emission tomography (PET), registered with structural magnetic resonance imaging (MRI) to investigate central glucose uptake in 17 males of a monogamous primate species, the titi monkey (Callicebus cupreus). Twelve pair-bonded males (including six with a lesion of the prefrontal cortex) and five lone males were scanned. The five lone males were re-scanned 48 h after pairing with a female. Significant differences in glucose uptake were found between males in long-term pair-bonds and lone males in areas including the nucleus accumbens, ventral pallidum, medial preoptic area, medial amygdala, and the supraoptic nucleus of the hypothalamus. In paired before and after comparisons, males showed significant changes following pairing in the right nucleus accumbens and ventral pallidum but not in other areas. Lesioned males showed significantly higher uptake in the posterior cingulate cortex than all other males. These results indicate some basic similarities between rodents and primates in the formation and maintenance of selective social bonds, but emphasize the importance of studying long-term maintenance in addition to short-term formation of social bonds.

This article, published in the Journal of Neurological Surgery, examines the diagnostic accuracy of beta-2 transferrin gel electrophoresis (B2Tf GE) in detecting cerebrospinal fluid (CSF) rhinorrhea. The study conducted a retrospective review of patients who presented with unilateral thin clear rhinorrhea (UTCR) and underwent B2Tf GE. The results showed that B2Tf GE had a sensitivity of 87.5%, specificity of 76.9%, positive predictive value of 77.8%, and negative predictive value of 87% in detecting CSF rhinorrhea. However, the study also highlighted the potential limitations of B2Tf GE and suggested considering other diagnostic tests in cases where B2Tf GE results deviate from clinical suspicion. [Extracted from the article]

Objectives: Unilateral clear thin rhinorrhea (UCTR) can be concerning for a nasal cerebrospinal fluid (CSF) leak. Beta‐2 transferrin electrophoresis has been the gold standard for initial non‐invasive confirmatory testing for CSF rhinorrhea, but there can be issues with fluid collection and testing errors. Ipratropium bromide nasal spray (IBNS) is highly effective at reducing rhinitis‐related rhinorrhea, and should presumably not resolve CSF rhinorrhea. This study assessed whether different clinical features and IBNS response helped predict presence or absence of CSF rhinorrhea. Methods: A prospective cohort study was conducted where all patients with UCTR had nasal fluid tested for beta‐2 transferrin, and were prescribed 0.06% IBNS. Patients were diagnosed with CSF rhinorrhea or other rhinologic conditions. Clinical variables like IBNS response (rhinorrhea reduction), positional worsening, salty taste, postoperative state, female gender, and body‐mass index were assessed for their ability to predict CSF rhinorrhea. Sensitivity, specificity, and predictive values and odds ratios were calculated for all clinical variables. Results: Twenty patients had CSF rhinorrhea, and 53 had non‐CSF etiologies. Amongst clinical variables assessed for predicting CSF absence or presence, significant associations were shown for IBNS response (OR = 844.66, p = 0.001), positional rhinorrhea worsening (OR = 8.22, p = 0.049), and body‐mass index ≥30 (OR = 2.92, p = 0.048). IBNS response demonstrated 96% sensitivity and 100% specificity, and 100% positive and 91% negative predictive values for predicting CSF rhinorrhea. Conclusions: In patients with UCTR, 0.06% IBNS response is an excellent screening tool for excluding CSF rhinorrhea, and should be considered in the diagnostic workup of CSF rhinorrhea. Level of Evidence: 2 Laryngoscope, 134:56–61, 2024 [ABSTRACT FROM AUTHOR]

New World monkeys represent an important but often poorly understood research resource. The relatively small size and low zoonotic risk of these animals make them appealing as research subjects in a number of areas. However, historic portrayal of many of these species as difficult to manage and handle is one of the factors that has limited their use. Basic guidelines are provided on management and handling approaches for the New World monkeys most commonly used in research: marmosets, squirrel monkeys, owl monkeys, and titi monkeys. Topics include transport and acclimation to a new facility, location changes within a facility, diet changes, removal from and return to social groups, capture and restraint, handling for anesthesia, postprocedural monitoring, and staff training.

The high sex ratio at birth in China has attracted considerable attentions from demographers. Previous studies assert that female infanticide, underreporting of female births, and prenatal sex-selective abortion were the immediate causes of the initial increase of the sex ratio at birth. Recent studies suggest that prenatal sex selection became the leading immediate cause of more recent increase in the sex ratio at birth. A snowball sampling survey conducted in rural Henan in 2001 collected information on women’s abortion histories. Using these data, we analyze the practice and mechanisms regarding to prenatal sex selection, as well as its impact on SRB. Results show that prenatal sex selection is widely known and commonly practiced in the studied area. The SRB is the highest among births that have only sister(s), and close to normal for other births. Using a population-average model, we found that female fetuses that have only sister(s) are most likely to be aborted. Finally, our imputation suggests that sex-selective abortion has been the predominant, if not the sole, immediate cause of the high SRB.

Young adults experience the highest rates of sexually transmitted diseases (STDs) in the United States and gender and racial/ethnic differentials in STD prevalence persist. Rich data are available to investigate an array of sociodemographic and behavioral risk factors that might explain variation in STD infection. These data also include biomarker test results enabling an investigation of current infection among a population-based sample of youth. We use data from Wave III of the National Longitudinal Study of Adolescent Health (Add Health) to examine sociodemographic and behavioral risk correlates of STDs, using nested binary logistic regression techniques. We consider whether respondents who refused or were unable to provide urine samples differ from those who provided urine samples. We also consider whether respondents whose specimens were not used, or whose specimens were used but for whom no definitive test result was obtained, differ from individuals for whom definitive test results were obtained. Finally, we explore sociodemographic and behavioral correlates of positive test results for those for whom definitive test results were obtained. All analyses are weighted and account for the complex study design of Add Health. Current STD infection is associated with a number of sociodemographic characteristics, including age, gender, and race/ethnicity, the effects of which differ depending on the specific pathogen. The effects of the sociodemographic characteristics remain even after accounting for differences in sexual risk behaviors. Future research should explore the contribution of partner characteristics and behaviors as well as sexual networks in explaining variation in STD infection.

Surveys in China conventionally sample from local area residential registers, which until recently have been of sufficient accuracy to function as de facto population registers. Due to a combination of large scale internal migration and massive replacement of housing in urban areas, a large fraction of the population currently does not live where registered. Individuals not living where registered are thus ineligible for inclusion in conventionally generated samples. Surveys whose samples depend on access to residential registers are inherently based on an under-enumeration of the population, as well as on a biased representation of the population due to exclusion of unregistered local residents. We report conclusions from, and observations related to, a pilot study designed to test the feasibility and effectiveness of a sampling method that does not depend on residential registers. In the pilot we (1) purposively selected small areas; (2) enumerated the small areas; (3) randomly sampled individuals from the enumeration lists; and (4) interviewed sampled individuals. This approach substantially reduced the underenumeration problem. As implemented, however, its point of departure required previously selected small areas. We describe an extension designed to achieve full coverage of the population of China through sampling of small areas as the penultimate stage of a multi-stage design.

Context: Adolescents have among the highest rates of STD, but until recently it has been difficult to characterize the multiple social and behavioral factors that affect STD risk because of measurement and methodological issues.Methods: Data from Wave I of the National Longitudinal Study of Adolescent Health (Add Health) are used to estimate effects of school, neighborhood, family, and individual characteristics on acquiring an STD. For sexually active teens, we also estimate the extent to which age at first intercourse affects STD acquisition. Additionally, we investigate the determinants of STD occurrence between Waves I and II of Add Health, and model the effects of prior STD acquisition. Random intercept logistic regression and random intercept piecewise exponential hazard regression are used to account for possible clustering in the Add Health data.Results: Overall, 7.0 percent of sexually active teens reported ever having an STD as of Wave I, and 6.7 percent reported having an STD between Waves I and II. Among all Wave I teens—uninitiated as well as sexually active—age, gender, race/ethnicity, family background characteristics, neighborhood and school characteristics affect STD acquisition. Among sexually active Wave I teens, those with a younger age at first intercourse are at greater risk of experiencing an STD. Other factors contribute, but to a lesser degree. For example, family structure becomes nonpredictive. For acquisition of an STD between Waves I and II, females, blacks, teens with lower levels of mother’s education, and those who had an STD previously are at higher risk.Conclusions: The findings support our hypothesis that multiple social and behavioral factors influence lifetime history of STD. Also, age at first intercourse and STD history are valid indicators of risk-related behavior.

Fox et al. (1998) carried out a logistic regression analysis with discrete covariates in which one of the covariates was missing for a substantial percentage of respondents. The missing data problem was addressed using the "approximate Bayesian bootstrap." We return to this missing data problem to provide a form of case study. Using the Fox et al. (1998) data for expository purposes we carry out a comparative analysis of eight of the most commonly used techniques for dealing with missing data. We then report on two sets of simulations based on the original data. These suggest, for patterns of missingness we consider realistic, that case deletion and weighted case deletion are inferior techniques, and that common simple alternatives are better. In addition, the simulations do not affirm the theoretical superiority of Bayesian Multiple Imputation. The apparent explanation is that the imputation model, which is the fully saturated interaction model recommended in the literature, was too detailed for the data. This result is cautionary. Even when the analyst of a single body of data is using a missingness technique with desirable theoretical properties, and the missingness mechanism and imputation model are supposedly correctly specified, the technique can still produce biased estimates. This is in addition to the generic problem posed by missing data, which is that usually analysts do not know the missingness mechanism or which among many alternative imputation models is correct.

Background and Objectives. Population parameter estimates for behavioral and contextual risk factors of STDs in individuals are currently unavailable. Surveillance data systems and clinical studies inherently can not provide this information. Nationally representative sample surveys that use self-reports of STD history are potentially better suited for this purpose. It remains to be established that self-reports are valid.Goal of this Study. Assess the validity of self-reports of STD history among school-going adolescents.Study Design. We compare gender and race/ethnicity differentials in self-report STD information in the mid-1990s National Longitudinal Survey of Adolescent Health (Add Health) with corresponding differentials obtained from CDC surveillance statistics.Results. Add Health and CDC surveillance data yield similar results. Further Add Health analysis demonstrates that family structure, socioeconomic status, and neighborhood context contribute to STD presence at the individual level.Conclusion. Self-reports of STD infection in a national sample of adolescents can be used to study behavioral and contextual risk factors.