Sites of Tubulin Polymerization in PC 12 Cells

The site at which tubulin enters into polymer in the neuritic process is a very important datum in terms of our understanding of the mechanism of transport of the microtubular cytoskeleton out the axon. If the form of tubulin being transported out the axon is the microtubule, then assembly of tubulin into microtubules should occur at or near the cell body; if, however, the form of tubulin transported is free tubulin dimer, then assembly can occur at any free microtubule end out the neurite. We have injected a fluorescent analog of tubulin into differentiated PC 12 cells and used differential extraction protocols to extract free dimer but not microtubules. We have imaged these cells before and after extraction by low-light-level video fluorescence microscopy and have used image analysis to examine the sites of tubulin incorporation into polymer or other unextracted components as a function of time. We find that tubulin in the distal reaches of the neurite is found initially as monomer and that its appearance in the unextracted component occurs later. This pattern of appearance of fluorescent tubulin initially in the soluble fraction and later in the unextractable component is qualitatively similar to that reported by other workers for biotinylated tubulin, but we see a larger gap between the rates of appearance in soluble fraction and in polymer. Quantitative analysis of fluorescence intensities in the two compartments with distance out the neurite reveals substantial variation between different neurites: In some neurites, the pattern of variation of unextracted/total tubulin suggests that tubulin enters into the unextracted component primarily near the cell body and that this unextracted component moves out the neurite with time, and in other neurites it suggest that monomer adds into microtubule ends staggered out the neurite. In no case do we see a pattern suggesting that distal addition predominates. These analyses of fluorescence intensities in extracted and unextracted neurites suggest that both transport of polymerized microtubules and monomer addition onto staggered microtubule ends occur in PC12 neurites and that in individual neurites one or the other of these two behaviors may predominate.     

Association of cardiovascular disease risk factors with socioeconomic position during childhood and during adulthood.

OBJECTIVE: To investigate strength of associations between risk factors for cardiovascular disease and socioeconomic position during childhood and adulthood. DESIGN: Cross sectional analysis of status of cardiovascular risk factors and past and present social circumstances. SUBJECTS: 5645 male participants in the west of Scotland collaborative study, a workplace screening study. MAIN OUTCOME MEASURES: Strength of association between each risk factor for cardiovascular disease (diastolic blood pressure, serum cholesterol concentration, level of recreational physical exercise, cigarette smoking, body mass index, and FEV1 score (forced expiratory volume in one second as percentage of expected value) and social class during childhood (based on father''s main occupation) and adulthood (based on own occupation at time of screening). RESULTS: All the measured risk factors were significantly associated with both father''s and own social class (P < 0.05), apart from exercise and smoking (not significantly associated with father''s social class) and body mass index (not significantly associated with own social class). For all risk factors except body mass index, the regression coefficient of own social class was larger than the regression coefficient of father''s social class. The difference between the coefficients was significant for serum cholesterol concentration, cigarette smoking, body mass index, and FEV1 score (all P < 0.001). CONCLUSIONS: Subjects'' status for behavioural risk factors (exercise and smoking) was associated primarily with current socioeconomic circumstances, while status for physiological risk factors (serum cholesterol, blood pressure, body mass index, and FEV1) was associated to varying extents with both past and present socioeconomic circumstances.     

Health and the life course: why safety nets matter.

This article argues that a life course approach is necessary to understand social variations in health. This is needed in order to take into account the complex ways in which biological risk interacts with economic, social, and psychological factors in the development of chronic disease. Such an approach reveals biological and social "critical periods" during which social policies that will defend individuals against an accumulation of risk are particularly important. In many ways, the authors of modern welfare states were implicitly addressing these issues, and the contribution of these policies to present day high standards of health in developed countries should not be ignored.     

Lifetime socioeconomic position and mortality: prospective observational study.

OBJECTIVES: To assess the influence of socioeconomic position over a lifetime on risk factors for cardiovascular disease, on morbidity, and on mortality from various causes. DESIGN: Prospective observational study with 21 years of follow up. Social class was determined as manual or non-manual at three stages of participants'' lives: from the social class of their father''s job, the social class of their first job, and the social class of their job at the time of screening. A cumulative social class indicator was constructed, ranging from non-manual social class at all three stages of life to manual social class at all three stages. SETTING: 27 workplaces in the west of Scotland. PARTICIPANTS: 5766 men aged 35-64 at the time of examination. MAIN OUTCOME MEASURES: Prevalence and level of risk factors for cardiovascular disease; morbidity; and mortality from broad causes of death. RESULTS: From non-manual social class locations at all three life stages to manual at all stages there were strong positive trends for blood pressure, body mass index, current cigarette smoking, angina, and bronchitis. Inverse trends were seen for height, cholesterol concentration, lung function, and being an ex-smoker. 1580 men died during follow up. Age adjusted relative death rates in comparison with the men of non-manual social class locations at all three stages of life were 1.29 (95% confidence interval 1.08 to 1.56) in men of two non-manual and one manual social class; 1.45 (1.21 to 1.73) in men of two manual and one non-manual social class; and 1.71 (1.46 to 2.01) in men of manual social class at all three stages. Mortality from cardiovascular disease showed a similar graded association with cumulative social class. Mortality from cancer was mainly raised among men of manual social class at all three stages. Adjustment for a wide range of risk factors caused little attenuation in the association of cumulative social class with mortality from all causes and from cardiovascular disease; greater attenuation was seen in the association with mortality from non-cardiovascular, non-cancer disease. Fathers having a manual [corrected] occupation was strongly associated with mortality from cardiovascular disease: relative rate 1.41 (1.15 to 1.72). Participants'' social class at the time of screening was more strongly associated than the other social class indicators with mortality from cancer and from non-cardiovascular, non-cancer causes. CONCLUSIONS: Socioeconomic factors acting over the lifetime affect health and risk of premature death. The relative importance of influences at different stages varies for the cause of death. Studies with data on socioeconomic circumstances at only one stage of life are inadequate for fully elucidating the contribution of socioeconomic factors to health and mortality risk.     

Birth weight and later socioeconomic disadvantage: evidence from the 1958 British cohort study.

OBJECTIVE--To investigate the relation between birth weight and socioeconomic disadvantage during childhood and adolescence in a birth cohort study. DESIGN--Longitudinal analysis of birth weight in relation to social class, household amenities and overcrowding, and financial difficulties as reported by parents at interview when participants were aged 7, 11, and 16 years; and receipt of unemployment or supplementary benefits as reported by participants at age 23. SUBJECTS--Male participants in the 1958 birth cohort (national child development study) born to parents resident in Great Britain during the week of 3-9 March 1958. Data on birth weight and financial difficulties between birth and 23 years were available for 4321; data on housing conditions and social class at ages 7, 11, and 16 years were available for 3370. MAIN OUTCOME MEASURES--Socioeconomic disadvantage at later ages in men weighing 6 lb (2721g) or under at birth compared with those weighing over 6 lb and between fifths of the distribution of birth weight. RESULTS--Cohort members who weighed 6 lb or under at birth were more likely to experience socioeconomic disadvantage subsequently. Those in lower fifths of the distribution were more likely to experience socioeconomic disadvantage. CONCLUSION--Low birth weight is associated with socioeconomic disadvantage in childhood and adolescence. Studies of the association of indicators of early development and adult disease need to take into account experiences right through from birth to adulthood if they are to elucidate the combination of risks attributable to developmental problems and socioeconomic disadvantage.     

The biology of the Yellowthroated Sandgrouse Pterocles gutturalis in a South African agricultural landscape

Tarboton, W.R., Blane, S. & Lloyd, P. 1999. The biology of the Yellowthroated Sandgrouse Pterocles gutturalis in a South African agricultural landscape. Ostrich 70 (3&4): 214–219.

A local population of Yellowthroated Sandgrouse was monitored from 1988–1992 at Northam, Northern Province, South Africa, a region in which this species was previously an irruptive, non-breeding visitor. Yellowthroated Sandgrouse were found to be year-round residents, foraging and nesting exclusively in areas cleared for agriculture, particularly one-year fallow lands. They ate the dry seeds of a variety of weedy plants, especially Amaranthus and Crotalaria spp. Males outnumbered females 1.35:1. Egg-laying occurred from April-October, with a peak in June. Clutch size (2–3) averaged 2.85 (n=26), and the incubation period for one nest was 26 days after clutch completion. Nesting success was estimated at 24.8% (n=19 nests, 176 nest days), and the daily nest predation rate at 2.55%; predation and ploughing accounted for most nest losses. Average annual productivity was estimated to be within the range 0.42–0.85 young/pair/year. We suggest that the Yellowthroated Sandgrouse depends on the seeds of early successional plants for food and that the recent agricultural development of the region maintains sufficient areas of fallow land to allow this otherwise nomadic species to become a breeding resident.     

Comprehensive passage (COMPASS) model: a model of downstream migration and survival of juvenile salmonids through a hydropower system

Migratory fish populations are impacted worldwide by river impoundments. Efforts to restore populations will benefit from a clear understanding of survival and migration process over a wide-range of river conditions. We developed a model that estimates travel time and survival of migrating juvenile salmonids (Oncorhynchus spp.) through the impounded Snake and Columbia rivers in the northwestern United States. The model allows users to examine the effects of river management scenarios, such as manipulations of river flow and spill, on salmonid survival. It has four major components: dam passage and survival, reservoir survival, fish travel time, and hydrological processes. The probability that fish pass through specific routes at a dam and route-specific survival probabilities were based on hydroacoustic, radio telemetry, PIT tag, and acoustic tag data. We related reservoir mortality rate (per day and per km) to river flow, water temperature, and percentage of fish passing through spillways and then fit the relationships to PIT-tag survival data. We related fish migration rate to water velocity, percentage of fish passing through spillways, and date in the season. We applied the model to two threatened “Evolutionarily Significant Units” (as defined under the US Endangered Species Act): Snake River spring/summer Chinook salmon (O. tshawytscha Walbaum) and Snake River steelhead (O. mykiss Walbaum). A sensitivity analysis demonstrated that for both species survival through the hydropower system was responsive to water temperature, river flow, and spill proportion. The two species, however, exhibited different patterns in their response. Such information is crucial for managers to effectively restore migratory fish populations in regulated rivers. Guest editors: R. L. Welcomme & G. Marmulla Hydropower, Flood Control and Water Abstraction: Implications for Fish and Fisheries     

Socio-Economic Position Has No Effect on Improvement in Health-Related Quality of Life and Patient Satisfaction in Total Hip and Knee Replacement: A Cohort Study

Introduction

Considerable evidence suggests that patients with more advantaged Socio-Economic Positions undergo Total Hip and Knee Replacement (THR/TKR) more often, despite having a lower need. We questioned whether more disadvantaged Socio-Economic Position is associated with an lower improvement in Health-Related Quality of Life (HRQoL) and a lower patient satisfaction after THR/TKR.

Methods

Patients who underwent primary THR/TKR in one academic and three community hospitals between 2005 and 2009, were eligible for inclusion. The highest completed levels of schooling were aggregated to index social class. We compared the improvement in HRQoL and postoperative satisfaction with surgery (measured using the Short-Form 36 (SF36) and an 11-point numeric rating scale of satisfaction) between the aggregated groups of highest completed levels of schooling, using linear mixed model analysis, with center as a random effect and potential confounders (i.e. age, gender, Body Mass Index and Charnley''s comorbidity classification) as fixed effects.

Results

586 THR patients and 400 TKR patients (40% of all eligible patients) agreed to participate and completed all questionnaires sufficiently. We found no differences in HRQoL improvement in any dimension of the SF36 in THR patients. Patients with a higher completed level of schooling had a larger improvement in role-physical (9.38 points, 95%-CI:0.34–18.4), a larger improvement in general health (3.67 points, 95%-CI:0.56–6.79) and a smaller improvement in mental health (3.60 points, 95%-CI:0.82–6.38) after TKR. Postoperative patient satisfaction did not differ between different highest completed level of schooling groups.

Discussion

Completed level of schooling has no effect on the improvement in HRQoL and patient satisfaction in a Dutch THR population and a small effect in a similar TKR population. Undertreatment of patients with more disadvantaged Socio-Economic Position cannot be justified, given the similar improvement in HRQoL and postoperative level of satisfaction with surgery between the social groups examined.