Statins and influenza mortality: systematic review and meta-analysis

Background

Due to their anti-inflammatory properties, it has been suggested that the use of statins could influence the evolution of influenza virus infection.

Objective

To evaluate the effect of statin therapy on mortality from influenza.

Material and methods

A meta-analysis that included studies evaluating the use of statins in patients with influenza and reporting data on mortality, after searching the PubMed/MEDLINE, Embase, and Cochrane Controlled Trials databases, was performed. A random effects model was applied. The risk of bias was analyzed and a sensitivity analysis was performed.

Results

Eight studies (10 independent cohorts), which included a total of 2,390,730 patients, were identified and eligible for analysis. A total of 1,146,995 subjects analyzed received statins, while 1,243,735 subjects were part of the control group. Statin therapy was associated with lower mortality (OR: 0.66; 95% CI: 0.51–0.85). The sensitivity analysis showed that the results were robust.

Conclusions

Our data suggest that, in a population with influenza, the use of statins was associated with a significant reduction in mortality. These results must be confirmed in future clinical trials.

Funding Acknowledgement

Type of funding sources: None.

Non-statin lipid-lowering therapy in coronary atherosclerosis regression: a meta-analysis and meta-regression

Introduction

Several studies have investigated the association between non-statin lipid-lowering therapy and regression of atherosclerosis. However, the studies were mostly small and their results were not always robust.

Objectives

(1) to define if a dual lipid-lowering therapy (statin ± non-statin drugs) is associated with coronary atherosclerosis regression, estimated by intravascular ultrasound (IVUS); (2) to assess the association between dual lipid-lowering-induced changes in LDL-C and non-HDL-C levels and atherosclerosis regression.

Methods

We performed a meta-analysis including trials of non-statin lipid-lowering therapy, reporting C-LDL, non-HDL-C and total atheroma volume (TAV) with a minimum of 6 months of follow-up. The primary endpoint was defined as the change in TAV measured from baseline to follow-up, comparing groups of subjects on statins alone versus combination of statin and non-statin drugs. The random-effects model and meta-regression were performed.

Results

Eight eligible trials of non-statin lipid-lowering drugs (1759 patients) were included. Overall, the dual lipid-lowering therapy was associated with a significant reduction in TAV [−3.5 mm3 (95% CI: −4.5 to −2.6)]; I2=11%]. In the analysis stratified according to the lipid-lowering drug class (ezetimibe or PCSK9 inhibitors), the findings were similar. In a meta-regression, a 10% decrease in LDL-C or non-HDL-C levels, was associated, respectively, with 0.92 mm3 and 1.05 mm3 regressions in TAV.

Conclusion

Our data suggest the addition of ezetimibe or PCSK9 inhibitors to statin therapy results in significantly increased regression of TAV. When the LDL-C and non-HDL-C levels reached were lower, the observed effect was also greater.

Forest Plot by Drugs Group

Funding Acknowledgement

Type of funding source: None

Bicuspid aortic valve: prompt identification of high-risk groups in a heterogeneous disease

Background

Bicuspid aortic valve (BAV) is a congenital heart disease that can be associated with aortic and/or valve complications. Although most BAV are predisposed to progressive calcification, little is known on variables related to significant valvular dysfunction. BAV is a heterogeneous disease, therefore it is important to identify high-risk groups for a closer follow- up and timely intervention.

Objective

Identify the main determinants of primary cardiovascular events (aortic valve replacement, aortic surgery and death) in a cohort of adults with BAV.

Methods

We included 325 consecutive patients with non-syndromatic BAV (2010–2019) referred to our hospital (3rd level). Clinical information was prospectively collected. All patients underwent serial echocardiograms and Cardiac CT was available in 125 patients (38%). We performed univariate and multivariate analyses and Kaplan-Meyer survival analysis with log-rank test. A p-value <0.05 was considered significant.

Results

325 patients (44.4±15.3 years, 73% men), right–left coronary cusp fusion (RL) in 79%,and presence of raphe in 77%. 100 patients (31.2%) had significant aortic valve dysfunction and 103 (31.7%) had aortic dialatation (>40mm) at the onset of the follow-up. Twenty-nine patients required cardiac surgery (8.9%, mainly symptomatic severe aortic stenosis with aortic valve replacement)and 3 died (1%) during a follow-up of 6.3±1.2 years. Patients with at least 2 of the following determinants at baseline: aortic valve prolapse, aortic valve calcification >1, age >50 years and/or aorta >45mm had higher risk of major cardiovascular events during follow-up (Chi2 for log rank test=27,229 p=0,000005).

Conclusions

In this study population of young adults with BAV we observed a high incidence of events related to the BAV. Age>50 years, aortic valve calcification, aortic valve prolapse and aortic dilatation were independently associated with primary cardiac events. Despite significant BAV heterogeneity, the identification of risk factors may help to stratify the risk of valvular dysfunction, aortic dilatation and major cardiovascular events.

BAV: Risk factors for cardiac surgery

Funding Acknowledgement

Type of funding source: None

Role of colchicine in stroke prevention: an updated meta-analysis

Background

Colchicine is a microtubule inhibitor with anti-inflammatory proprieties. As the body and quality of evidence regarding the efficacy of colchicine for cardiovascular prevention is controversial, the aims of this study was to evaluate the effect of colchicine therapy on vascular events.

Methods

A meta-analysis was performed of randomized controlled clinical trials of colchicine on high cardiovascular risk populations, reporting data from stroke, myocardial infarction, cardiovascular mortality and all-cause mortality, after searching the PubMed/MEDLINE, Embase and Cochrane Controlled Trials databases. A random-effects meta-analysis model was then applied.

Results

Nine eligible trials of colchicine therapy, involving a total of 6630 patients, were considered eligible for analysis (3359 subjects were allocated to receive colchicine while 3271 subjects were allocated to the respective control arms). The stroke incidence was lower in the colchicine group compared with placebo arm (OR, 0.33; 95% CI, 0.15–0.70; six studies evaluated). We did not find a significant reduction in the incidence of myocardial infarction, cardiovascular mortality or all-cause mortality.

Conclusion

Our data suggest that in a population with high cardiovascular risk, the use of colchicine results in significantly reduction on stroke risk. Colchicine is an accessible drug that could be successfully utilized for the prevention of atherosclerotic cerebrovascular disease. The tolerability and benefits should be confirmed in ongoing clinical trials.

Forest Plot Primary endpoint

Funding Acknowledgement

Type of funding source: None

P811 More than aortic measurements: evaluation with TTE and angioCT in bicuspid aortic valve yields useful information about valvular compromise

Background

2D transthoracic echocardiogram (TTE) is the technique of choice in the diagnosis of bicuspid aortic valve (BAV). Computed tomography (CT) is widely used in BAV to measure aortic diameters. However, in some cases CT or magnetic resonance (MRI) can add important information to TTE regarding valvular degeneration and morphotype.

We designed the present prospective study to determine the agreement between TTE and gated CT in the assessment of aortic valve morphology, fibrosis, calcification and measurements of thoracic aorta. We also aimed to analyze the utility of CT in the evaluation of BAV patients, in addition to aortic measurements.

Methods

We included 30 consecutive patients with BAV (mean age 45 ± 15.7 years ; 73.3% men) who underwent both TTE and ECG-gated cardiac and aortic CT for valvular and aortic assessment in a follow-up protocol with a time interval between TTE and CT of 4 ± 2.6 months.

We performed measurements of thoracic aorta at 6 levels (annulus, Valsalva sinus: VS, sinotubular junction, ascendent, arch and isthmus) with both techniques following guideline recommendations blinded to the results of the other technique.

Several measurements of VS were performed in short-axis view (double-oblique method) (maximal diameter perpendicular to the valve opening, sinus to sinus, raphe to sinus, commissure to commissure) at systole and diastole with CT.

Valve phenotype, presence of raphe, calcification scoring, aortic valve prolapse and fibrosis were also determined with both techniques and maximum aortic diameters were compared. An indexed aortic diameter > 21 mm/m2 was considered as aortic dilation and assimetryc root was defined when differences between CT measurements were ≥5mm.

Results

In 7 patients (23.3%) aortic diameter differences at Sinus by TTE and CT were ≥3mm. Concerning ascending aorta measurements, there was better agreement and only 2 cases (6.6%) showed differences ≥ 3mm.

In 2 patients with severe calcification valve morphology was identified only with CT. There was good agreement between TTE and CT in calcium quantification in patients with valvular calcium score over 2000 AU (n = 5) and in those without calcification. However, TTE failed in identification of valvular fibrosis in 5 patients.

10 patients (30%) had aortic dilatation with CT and 7 according to TTE measurements. The 3 patients that were not identified as dilated in TTE had dilatation at the distal tubular portion.

CT led to identification of coronary anomalies in 5 patients (16.7%), most of them anomalous high origin above the sinotubular junction.

Conclusions

Although TTE is the gold-standard in the diagnosis and follow-up of patients with BAV, CT was useful to confirm aortic measurements and to identify valvular fibrosis, assimetry, coronary anomalies and dilatation at the tubular portion. CT can add important information to TTE regarding valvular morphotype and aortic measurements, although radiation and cost should be evaluated.

Abstract P811 Figure. Calcification agreement TTE and CT

P667Aspirin in primary prevention. Risks and benefits. Up date 2019. A meta-analysis

Objectives

1. Perform an updated meta-analysis on the use of aspirin in primary cardiovascular prevention. 2. Analyze the results by risk.

Methods

This meta-analysis was performed according to the PRISMA guidelines. The primary endpoint was cardiovascular death, AMI, and ischemic stroke. The measures of effect size are expressed as odds ratios. The level of statistical significance was established at 0.05.

Characteristics of the studies Trials Year N Follow-up Risk RTPDABMD 1988 5,139 5.5 Middle PHS 1989 22,071 5 Low HOT 1998 18,790 3.8 Middle TPT 1998 5,085 6.7 Middle PPP 2001 44,95 3.6 Low WHS 2005 39,876 10.1 Low JPAD 2008 2,539 4.4 Low POPADAD 2008 1276 6.7 High AAA 2010 3,350 8.2 Low JPPP 2014 14,464 5 Low ASCEND 2018 15,480 7.4 Middle ARRIVE 2018 12,546 5 Low ASPREE 2018 19,114 4.7 Low RTPDABMD, Randomised trial of prophylactic daily aspirin in British male doctors; PHS, Physicians' Health Study; HOT, Hypertension Optimal Treatment; TPT, Thrombosis Prevention Trial; PPP, Primary Prevention Project; WHS, Women's Health Study; JPAD, Japanese Primary Prevention of Atherosclerosis With Aspirin for Diabetes; POPADAD, Prevention of Progression of Arterial Disease and Diabetes; AAA, Aspirin for Asymptomatic Atherosclerosis; JPPP, Japanese Primary Prevention Project; ASCEND, A Study of Cardiovascular Events in Diabetes; ARRIVE, Aspirin to Reduce Risk of Initial Vascular Events; ASPREE, Aspirin in Reducing Events in the Elderly.

Figure 1

Results

Thirteen works were considered for the analysis (Table 1). A total of 164,225 patients were included, 82,900 in the aspirin arm and 81,325 in the control group. A reduction of the primary endpoint was observed in the AAS group (OR 0.90, 95% CI 0.85–0.94). No differences by risk group (Figure 1). Risk of severe bleeding was significantly higher in patients treated with ASA (OR 1.45, 95% CI 1.34–1.56), this difference was maintained by risk (Figure 1).

Acknowledgement/Funding

None

Modulations of the Optical Flow Did Not Induce Locomotor Pattern Fluctuations in Treadmill Walking in Man

We report an analysis of gait during human treadmill walking when visual information from the self-displacement velocity was modulated. Removing or sinusoidally modulating the frequency edge information in the optical flow did not induce significant changes in the walking velocity as analyzed using Fast Fourier Transform or in the spatiotemporal gait parameters. While low-frequency fluctuations in displacement speed increased, there was no significant change in locomotor cycle stability. When a constant frequency edge was provided, i.e., when a backward optical flow was added, stride length decreased as compared to the no-optical-flow condition and instantaneous fluctuations in stride amplitude increased. Temporal gait parameters did not change. These partial effects might be better explained by modifications in trunk balance. In humans, modulation of velocity information on self-motion cannot induce unintentional modulation of walking velocity and did not enhance fluctuations in the locomotor pattern. These results argue against the proprioceptive role of sagittal visual-motion information in control of stability of rhythmic leg movement, at least when other proprioceptive feedback sources are available.

Contribution of limb momentum to power transfer in athletic wheelchair pushing

Pushing capacity is a key parameter in athletic racing wheelchair performance. This study estimated the potential contribution of upper limb momentum to pushing. The question is relevant since it may affect the training strategy adopted by an athlete. A muscle-free Lagrangian dynamic model of the upper limb segments was developed and theoretical predictions of power transfer to the wheelchair were computed during the push phase. Results show that limb momentum capacity for pushing can be in the order of 40J per push cycle at 10m/s, but it varies with the specific pushing range chosen by the athlete. Although use of momentum could certainly help an athlete improve performance, quantifying the actual contribution of limb momentum to pushing is not trivial. A preliminary experimental investigation on an ergometer, along with a simplified model of the upper limb, suggests that momentum is not the sole contributor to power transfer to a wheelchair. Muscles substantially contribute to pushing, even at high speeds. Moreover, an optimal pushing range is challenging to find since it most likely differs if an athlete chooses a limb momentum pushing strategy versus a muscular exertion pushing strategy, or both at the same time. The study emphasizes the importance of controlling pushing range, although one should optimize it while also taking the dynamics of the recovery period into account.

Seasonal gonadal development and age-related maturity patterns of introduced pumpkinseed (Lepomis gibbosus Linnaeus, 1758) in a heated thermal reservoir and an adjacent river reach

Testis and ovarian maturation status, maturity profile and gonado-somatic index (GSI) were assessed in pumpkinseed (Lepomis gibbosus) collected from Mirgenbach, a cooling-water reservoir associated with a nuclear power plant, and from the River Moselle 7km downstream of the reservoir's thermal outflow. Histological investigation indicated that in both sexes, gonadal development of pumpkinseed in the heated reservoir was more advanced than in the cooler Moselle River throughout the breeding season. The histological maturity profile of reservoir males ranked by the advancement of sperm cells was highly correlated with its GSI (rs=0.73, P<0.001). GSI of females in the reservoir increased with the stage at maturity, but GSI was not significantly correlated with total length, age or growth rate of the individual. All sampled individuals of both sexes were mature at age 1 in the heated reservoir, whereas 48% of age 1 males and 57% of age 1 females were not mature in the river. GSI patterns suggest that males in the reservoir adopted one of two reproductive strategies (nesters or cuckolders), whereas no small males with large enough testes to be considered cuckolders were apparent in the river. The warm thermal regime of Mirgenbach Reservoir led to precocial maturity, early season reproduction, and the greater prevalence of apparent cuckolder males than would normally occur in this climatic zone.

A rare missense mutation in CHRNA4 associates with smoking behavior and its consequences

Using Icelandic whole-genome sequence data and an imputation approach we searched for rare sequence variants in CHRNA4 and tested them for association with nicotine dependence. We show that carriers of a rare missense variant (allele frequency=0.24%) within CHRNA4, encoding an R336C substitution, have greater risk of nicotine addiction than non-carriers as assessed by the Fagerstrom Test for Nicotine Dependence (P=1.2 × 10(-4)). The variant also confers risk of several serious smoking-related diseases previously shown to be associated with the D398N substitution in CHRNA5. We observed odds ratios (ORs) of 1.7-2.3 for lung cancer (LC; P=4.0 × 10(-4)), chronic obstructive pulmonary disease (COPD; P=9.3 × 10(-4)), peripheral artery disease (PAD; P=0.090) and abdominal aortic aneurysms (AAAs; P=0.12), and the variant associates strongly with the early-onset forms of LC (OR=4.49, P=2.2 × 10(-4)), COPD (OR=3.22, P=2.9 × 10(-4)), PAD (OR=3.47, P=9.2 × 10(-3)) and AAA (OR=6.44, P=6.3 × 10(-3)). Joint analysis of the four smoking-related diseases reveals significant association (P=6.8 × 10(-5)), particularly for early-onset cases (P=2.1 × 10(-7)). Our results are in agreement with functional studies showing that the human α4β2 isoform of the channel containing R336C has less sensitivity for its agonists than the wild-type form following nicotine incubation.

Assessment of sediment concentration and nutrient loads in effluents drained from extensively managed fishponds in France

Expansion of aquaculture has increased concern over its environmental impact. The composition of effluents from intensive aquaculture is well documented, but few data on extensive aquaculture are available. During 12 draining operations, 523 water samples were collected downstream from six extensively-managed fishponds in northeastern France. Study ponds had surface areas of 2-620 ha and were managed for production of Cyprinids and Percids. Concentrations of total suspended solids, total phosphorus, and Kjeldahl nitrogen in effluents from the ponds were greatest during the final stage of draining. Loads of phosphorus were higher than those reported for effluents of more intensive aquaculture ponds in the USA, but the source of the potential pollutants was catchments and sediment rather than feeds and fertilizer. It will be necessary to reduce the water drawdown rate during the fishing stage and possibly implement other best management practices to prevent the TSS concentration from exceeding 1 g/L.

CDKN2A mutations and melanoma risk in the Icelandic population

BACKGROUND

Germline CDKN2A mutations have been observed in 20-40% of high risk, melanoma prone families; however, little is known about their prevalence in population based series of melanoma cases and controls.

METHODS

We resequenced the CDKN2A gene, including the p14ARF variant and promoter regions, in approximately 703 registry ascertained melanoma cases and 691 population based controls from Iceland, a country in which the incidence of melanoma has increased rapidly.

RESULTS

We identified a novel germline variant, G89D, that was strongly associated with increased melanoma risk and appeared to be an Icelandic founder mutation. The G89D variant was present in about 2% of Icelandic invasive cutaneous malignant melanoma cases. Relatives of affected G89D carriers were at significantly increased risk of melanoma, head and neck cancers, and pancreatic carcinoma compared to relatives of other melanoma patients. Nineteen other germline variants were identified, but none conferred an unequivocal risk of melanoma.

CONCLUSIONS

This population based study of Icelandic melanoma cases and controls showed a frequency of disease related CDKN2A mutant alleles ranging from 0.7% to 1.0%, thus expanding our knowledge about the frequency of CDKN2A mutations in different populations. In contrast to North America and Australia where a broad spectrum of mutations was observed at a similar frequency, in Iceland, functional CDKN2A mutations consist of only one or two different variants. Additional genetic and/or environmental factors are likely critical for explaining the high incidence rates for melanoma in Iceland. This study adds to the geographic regions for which population based estimates of CDKN2A mutation frequencies are available.

[Episiotomy and prevention of perineal and pelvic floor injuries]

OBJECTIVES

The objective of this review was to assess the efficacy of episiotomy to prevent severe perineal tears, urinary incontinence, faecal incontinence and genital prolapse.

MATERIAL AND METHODS

A systematic review on Medline database was performed between 1980 and 2005. One hundred seventy seven articles were selected. Trial quality was assessed on the following parameters: design (prospective, randomized, meta-analysis), sample size (>50) and relevant results. Finally, 43 articles were analysed.

RESULTS

The routine use of episiotomy did not prevent severe perineal tears. It decreased the risk of moderate anterior perineal lacerations. The risk of severe perineal tears during episiotomy increased in the following circumstances: primiparity, Asian women, perineal length<or=3cm, forceps or vacuum-assisted deliveries and macrosomia. Relevant studies were consistent in demonstrating no benefit for routine episiotomy to prevent urinary or faecal incontinence or pelvic floor relaxation, even if there is a lack of data concerning long-term effects on pelvic floor support.

CONCLUSION

The routine use of episiotomy to prevent severe perineal tears, urinary incontinence, faecal incontinence and genital prolapse should be abandoned.

Perinatal care regionalization and acceptability by professionals in France

BACKGROUND

For twenty years, most of industrial countries developed recommendations on regionalization of perinatal care. Perinatal regionalization is particularly aimed at improving morbidity and mortality outcomes of low birth weight newborns by transferring pregnant women to the maternity units having a medical or neonatal environment suited to the risks incurred by mothers or babies. Perinatal regionalization cannot be effective without being well accepted by the majority of professionals. The objectives of this study were then to identify professionals'expectations and objections to perinatal regionalisation and to compare them from a professional group to another one.

METHODS

Professionals of 3 French perinatal networks were under consideration: the Rhône, the Auvergne and the Gard-Lozère networks. The study included two stages: 1) a psychosociological qualitative study, based on professionals'interviews, aimed at identifying main concerns of professionals and developing a questionnaire; then 2) an epidemiological quantitative study, using this questionnaire within French networks. In the questionnaire, 8 dimensions explored the professionals'views: constraints related to regulation aspects and to the setting up of maternity units care levels, risk of loss of professionals' competence and prestige, consequences on medical practices, on inter-professional relationship, on work organization and financial aspects, and related to the new role of 'private practice'professionals, legal consequences.

RESULTS

The response rate of the epidemiological study was 80%. The results permitted to construct 8 dimension scores describing the reasons of poor acceptability of regionalization. After taking into account the age, the sex, the network and the juridical status of the institution, the study revealed a significant poorer acceptability of regionalization by most of medical specialty groups (anesthetists, obstetricians, midwives and "private practice" professionals) compared with neonatologists, or by "private" professionals (professionals working in private clinics and "private practice" professionals) compared with professionals working in university or community hospitals. The study described also network setting up conditions related to its functioning.

CONCLUSION

By identifying clearly professionals 'objections and expectations, this study should facilitate improvement in the organization of studied perinatal networks.

[Neonatal consequences of maternal smoking during pregnancy]

In utero tobacco consumption is a serious public health problem in France; it is very frequent and the long term consequences are not only numerous but also misinterpreted by our population. 25 to 29% of women arrive at the end of their pregnancy without stopping smoking and 50% of non smoking mothers live in an environment polluted by tobacco during pregnancy. The authors would like to stress the gravity of this situation. At the maternity hospital in Nîmes, 358 women who gave birth at term and after a normal pregnancy were enrolled in a survey and monitored with thiocyanate for their tobacco consumption. Birth weight, height, and cranial perimeter of the infants were noted at birth. Results confirmed earlier work on this subject: the three variables studied were consistently weakened by the mother's addiction to tobacco. The authors recall previous medical literature on the pathophysiology and other consequences on the brain: such as I.Q. behavior, sudden infant death syndrome, vascular alterations with possible long-term complications, as well as pulmonary alterations on which there has recently been much research. The question is raised as to why this problem is so neglected in our society and what could be done to change this state of affairs.

A new, stereocontrolled approach to iminosugar C-glycosides from L-sorbose

The efficient synthesis of the iminoalditols derivatives 1 and 2 (nojirimycin alpha-C-glycosides) has been achieved in 10 steps from commercially available 2,3;4,6-di-O-isopropylidene-alpha-L-sorbofuranose in an overall yield of 23-27%.

Visual perception modifies goal-directed movement control: supporting evidence from a visual perturbation paradigm

It is well known that dynamic visual information influences movement control, whereas the role played by background visual information is still largely unknown. Evidence coming mainly from eye movement and manual tracking studies indicates that background visual information modifies motion perception and might influence movement control. The goal of the present study was to test this hypothesis. Subjects had to apply pressure on a strain gauge to displace in a single action a cursor shown on a video display and to immobilize it on a target shown on the same display. In some instances, the visual background against which the cursor moved was unexpectedly perturbed in a direction opposite to (Experiment 1), or in the same direction as (Experiment 2) the cursor controlled by the subject. The results of both experiments indicated that the introduction of a visual perturbation significantly affected aiming accuracy. These results suggest that background visual information is used to evaluate the velocity of the aiming cursor, and that this perceived velocity is fed back to the control system, which uses it for on-line corrections.

Postural effects of motion vision in young autistic children

We present the first assessment of motion vision in childhood autism. Postural reactivity to visually perceived motion was measured in five autistic children and 12 normal controls of the same chronological age. Anteroposterior as well as total body sway occurring on a force platform in response to movements in the visual environment were compared. Autistic children were posturally more unstable than normal children and quite insensitive to visually perceived environmental motion. Some implications of this impairment for sensorimotor and social communication development in infantile autism are discussed.

Effects of stationary and moving textured backgrounds on the visuo-oculo-manual tracking in humans

We investigated the effects of stationary and moving textured backgrounds on ocular and manual pursuit of a discrete target that suddenly starts to move at constant speed (ramp motion). When a stationary textured background was superimposed to the target displacement, the gain of the steady-state eye smooth pursuit velocity was significantly reduced, while the latency of pursuit initiation did not vary significantly, as compared to a dark background condition. The initial velocity of the eye smooth pursuit was also lowered. Both the initial acceleration and the steady-state manual tracking angular velocity were slightly, but not significantly, lowered when compared to a dark background condition. Detrimental effects of the stationary textured background were of comparable amplitude (approximately 10%) for ocular and manual pursuit. In a second condition, we compared ocular and manual pursuit when the textured background was either stationary or drifting. Initial and steady-state eye velocities increased when the textured background moved in the same direction as the target. Conversely, when the background moved in the opposite direction, both velocities were decreased. Eye displacement gain remained however close to unity due to an increase in the occurrence of catch-up corrective saccades. The effects of the moving backgrounds on the initial and steady-state forearm velocities were inverse to that reported for smooth pursuit eye movements. Neither manual nor ocular smooth pursuit latencies were affected.

Effects of the spatio-temporal structure of optical flow on postural readjustments in man

How does the spatio-temporal structure of an oscillating radial optical flow affect postural stability? In order to investigate this problem, two different types of stimulus pattern were presented to human subjects. These stimuli were generated either with a constant spatial frequency or with a spatial frequency gradient providing monocular depth cues. When the stimulation was set in motion, the gain response of the antero-posterior postural changes depended upon the oscillation frequency of the visual scene. The amplitude of the postural response did not change with the amplitude of the visual scene motion. The spatial orientation of the postural sway (major axis of sway) depended strictly and solely on the structure of the visual scene. In static conditions, depth information resulting from the presence of a spatial frequency gradient enhanced postural stability. When set in motion, a visual scene with a spatial frequency gradient induced an organization of postural sway in the direction of the visual motion. Considering visual dynamic cues, postural instability depended linearly both on the logarithm of the velocity and on the logarithm of the temporal frequency. A nonlinear relationship existed between the amplitude of the fore-aft postural sway at the driving frequency and the temporal frequency, with a peak around 2-4 Hz. These results are discussed in terms of their implications for the separation of visual and biomechanical factors influencing visuo-postural control.

Low luminance contrast sensitivity: effects of training on psychophysical and optokinetic nystagmus thresholds in man

We compared psychophysical contrast sensitivity function (psi-CSF) and optokinetic contrast sensitivity function (OKN-CSF) in man, for the combination of three spatial and three temporal frequencies. psi-CSF was defined as the inverse of the contrast threshold, that is the contrast value of a sinusoidal grating for which a subject was able to identify the width of a drifting grating. OKN-CSF was defined as the inverse of the contrast value of the grating which triggered an involuntary optokinetic nystagmus. In highly experienced subjects, OKN-CSF was overall higher than psi-CSF. More precisely, differences between both contrast sensitivity functions occurred mainly in the low spatio-temporal frequency range (below 4 c/deg and 9 Hz). In naive subjects, psi-CSF reached the level of OKN-CSF after two consecutive test sessions. OKN-CSF did not change with training. Similarly, high spatio-temporal frequency psychophysical thresholds did not change with training and, moreover, approximated OKN-CSF thresholds. Low spatio-temporal frequency psychophysical sensitivity was initially lower than corresponding OKN-CSF sensitivity; however, after only two training sessions, the two functions were indistinguishable due to a selective increase in psychophysical low spatio-temporal frequency sensitivity.

Modulations of the optical flow did not induce locomotor pattern fluctuations in treadmill walking in man

We report an analysis of gait during human treadmill walking when visual information from the self-displacement velocity was modulated. Removing or sinusoidally modulating the frequency edge information in the optical flow did not induce significant changes in the walking velocity as analyzed using Fast Fourier Transform or in the spatiotemporal gait parameters. While low-frequency fluctuations in displacement speed increased, there was no significant change in locomotor cycle stability, When a constant frequency edge was provided, i.e., when a backward optical flow was added, stride length decreased as compared to the no-optical-flow condition and instantaneous fluctuations in stride amplitude increased. Temporal gait parameters did not change. These partial effects might be better explained by modifications in trunk balance. In humans, modulation of velocity information on self-motion cannot induce unintentional modulation of walking velocity and did not enhance fluctuations in the locomotor pattern. These results argue against the proprioceptive role of sagittal visual-motion information in control of stability of rhythmic leg movement, at least when other proprioceptive feedback sources are available.

Dopaminergic modulation of visual sensitivity in man

A large body of experimental evidence supports the hypothesis that dopamine is a functional neuromodulator at many levels of the visual system. Intrinsic dopaminergic neurons were characterized in most mammalian retina, including man. These neurons give rise to a dendritic plexus covering the retina. Thus, dopamine seems to be involved in the organization of the ganglion cell and the bipolar cell receptive fields and modulates physiological activity of photoreceptors, both processes which underlie sensitivity and spatial selectivity of visual processing in the early stage of the visual system. Moreover, few data are now available concerning the functional significance of dopaminergic modulation of visual sensitivity in man. Parkinson's disease is a specific disorder of central dopaminergic systems. Abnormalities in the pattern-evoked potentials and electroretinogram have been found in parkinsonian patients. Contrast sensitivity, a useful tool for measuring visual spatio-temporal sensitivity in man, has also been shown to be modified due to this affection. Dynamic contrast sensitivity is primarily decreased in these patients, distinguishing them from the normal aging process. Because these modifications in shape of the contrast sensitivity function are reversed by L-Dopa, and that neuroleptic administration could reproduce them in schizophrenia patients, it was suggested that dopamine might tune the contrast sensitivity function in man. We have recently shown that subcutaneous apomorphine induces changes in contrast sensitivity in healthy volunteers, which preferentially affect motion sensitivity. These dopaminergic sensitive modifications in the shape of the contrast sensitivity function might reflect a change in the range of sensitivity of the visual system, both in dynamic and spatial properties. This could be explained by a modification in the spatial and dynamic properties of the ganglion cell responses in the retina. Moreover, we suggest both from our results and from the review of the literature that human psychophysical data confirm the hypothesis that dopamine may be involved in light retinal adaptation, as light-induced and dopamine-induced modifications in the shape in the contrast sensitivity function are quite similar.

Rabies RNA synthesis, detected with cDNA probes, as a marker for virus transport in the rat nervous system

The kinetics of viral RNA synthesis in different parts of the rat brain, infected with fixed or street rabies virus strains, is correlated with their anatomical neuronal connections with the masseter muscles, using hybridization with rabies cDNA probes. Viral RNA synthesis is first detected in the brain-stem and in the pons where the direct anatomical projection of the masseter muscle nervous arborization into the sensory and motor nuclei is located, through the trigeminus nerve. Rabies RNA detection is delayed in the other regions of the rat brain depending on the time course of virus transport from the trigeminal nuclei through multiple nervous connections.

Selective effects of low doses of apomorphine on spatiotemporal contrast sensitivity in healthy volunteers: a double-blind placebo-controlled study

1. Apomorphine (1 and 5 micrograms kg-1) and placebo were given to nine normal volunteers, using a Latin-square design and double-blind procedures. The visual perception of static and moving patterns (static and motion contrast sensitivity) was evaluated before and 15 min after the dose administration. 2. Apomorphine (1 and 5 micrograms kg-1), as compared with placebo, led to a significant overall reduction of the visual perception of movement. This effect was dose-related, and apomorphine (5 micrograms kg-1) induced a more pronounced decrease in the visual perception of movement than apomorphine (1 microgram kg-1). With apomorphine (5 micrograms kg-1), the reduction was more pronounced for low spatial frequencies, and was linearly inversely correlated to the spatial frequency for a temporal frequency of 3 Hz. Finally, no significant effect of apomorphine was observed for sensitivity to static patterns. 3. Several non exclusive hypotheses may be suggested: The effects of apomorphine may result from stimulation of retinal D1- and/or D2-dopaminergic receptors. Apomorphine may increase the surround inhibition of ganglion cells' receptive-fields. This modification of the centre-surround balance may explain the decrease in contrast sensitivity for low spatial frequencies. The specific effects of apomorphine on the visual perception of movement support the hypothesis that apomorphine preferentially affects the magnocellular pathway which mediates sensitivity to moving patterns.