Corrigendum: Building an open source classifier for the neonatal EEG background: a systematic feature-based approach from expert scoring to clinical visualization

[This corrects the article DOI: 10.3389/fnhum.2021.675154.].

FOXG1 variants can be associated with milder phenotypes than congenital Rett syndrome with unassisted walking and language development

Since 2008, FOXG1 haploinsufficiency has been linked to a severe neurodevelopmental phenotype resembling Rett syndrome but with earlier onset. Most patients are unable to sit, walk, or speak. For years, FOXG1 sequencing was only prescribed in such severe cases, limiting insight into the full clinical spectrum associated with this gene. Next-generation sequencing (NGS) now enables unbiased diagnostics. Through the European Reference Network for Rare Malformation Syndromes, Intellectual and Other Neurodevelopmental Disorders, we gathered data from patients with heterozygous FOXG1 variants presenting a mild phenotype, defined as able to speak and walk independently. We also reviewed data from three previously reported patients meeting our criteria. We identified five new patients with pathogenic FOXG1 missense variants, primarily in the forkhead domain, showing varying nonspecific intellectual disability and developmental delay. These features are not typical of congenital Rett syndrome and were rarely associated with microcephaly and epilepsy. Our findings are consistent with a previous genotype-phenotype analysis by Mitter et al. suggesting the delineation of five different FOXG1 genotype groups. Milder phenotypes were associated with missense variants in the forkhead domain. This information may facilitate prognostic assessments in children carrying a FOXG1 variant and improve the interpretation of new variants identified with genomic sequencing.

An automated bedside measure for monitoring neonatal cortical activity: a supervised deep learning-based electroencephalogram classifier with external cohort validation

BACKGROUND

Electroencephalogram (EEG) monitoring is recommended as routine in newborn neurocritical care to facilitate early therapeutic decisions and outcome predictions. EEG's larger-scale implementation is, however, hindered by the shortage of expertise needed for the interpretation of spontaneous cortical activity, the EEG background. We developed an automated algorithm that transforms EEG recordings to quantified interpretations of EEG background and provides simple intuitive visualisations in patient monitors.

METHODS

In this method-development and proof-of-concept study, we collected visually classified EEGs from infants recovering from birth asphyxia or stroke. We used unsupervised learning methods to explore latent EEG characteristics, which guided the supervised training of a deep learning-based classifier. We assessed the classifier performance using cross-validation and an external validation dataset. We constructed a novel measure of cortical function, brain state of the newborn (BSN), from the novel EEG background classifier and a previously published sleep-state classifier. We estimated clinical utility of the BSN by identification of two key items in newborn brain monitoring, the onset of continuous cortical activity and sleep-wake cycling, compared with the visual interpretation of the raw EEG signal and the amplitude-integrated (aEEG) trend.

FINDINGS

We collected 2561 h of EEG from 39 infants (gestational age 35·0-42·1 weeks; postnatal age 0-7 days). The external validation dataset included 105 h of EEG from 31 full-term infants. The overall accuracy of the EEG background classifier was 92% in the whole cohort (95% CI 91-96; range 85-100 for individual infants). BSN trend values were closely related to the onset of continuous EEG activity or sleep-wake cycling, and BSN levels showed robust difference between aEEG categories. The temporal evolution of the BSN trends showed early diverging trajectories in infants with severely abnormal outcomes.

INTERPRETATION

The BSN trend can be implemented in bedside patient monitors as an EEG interpretation that is intuitive, transparent, and clinically explainable. A quantitative trend measure of brain function might harmonise practices across medical centres, enable wider use of brain monitoring in neurocritical care, and might facilitate clinical intervention trials.

FUNDING

European Training Networks Funding Scheme, the Academy of Finland, Finnish Pediatric Foundation (Lastentautiensäätiö), Aivosäätiö, Sigrid Juselius Foundation, HUS Children's Hospital, HUS Diagnostic Center, National Health and Medical Research Council of Australia.

Asymmetry in sleep spindles and motor outcome in infants with unilateral brain injury

AIM

To determine whether interhemispheric difference in sleep spindles in infants with perinatal unilateral brain injury could link to a pathological network reorganization that underpins the development of unilateral cerebral palsy (CP).

METHOD

This was a multicentre retrospective study of 40 infants (19 females, 21 males) with unilateral brain injury. Sleep spindles were detected and quantified with an automated algorithm from electroencephalograph records performed at 2 months to 5 months of age. The clinical outcomes after 18 months were compared to spindle power asymmetry (SPA) between hemispheres in different brain regions.

RESULTS

We found a significantly increased SPA in infants who later developed unilateral CP (n=13, with the most robust interhemispheric difference seen in the central spindles. The best individual-level prediction of unilateral CP was seen in the centro-occipital spindles with an overall accuracy of 93%. An empiric cut-off level for SPA at 0.65 gave a positive predictive value of 100% and a negative predictive value of 93% for later development of unilateral CP.

INTERPRETATION

Our data suggest that automated analysis of interhemispheric SPA provides a potential biomarker of unilateral CP at a very early age. This holds promise for guiding the early diagnostic process in infants with a perinatally identified brain injury.

WHAT THIS PAPER ADDS

Unilateral perinatal brain injury may affect the development of electroencephalogram (EEG) sleep spindles. Interhemispheric asymmetry in sleep spindles can be quantified with automated EEG analysis. Spindle power asymmetry can be a potential biomarker of unilateral cerebral palsy.

Attitudes towards urban green during the COVID-19 pandemic via Twitter

COVID-19 has had economic, social and environmental impacts worldwide. Governments have adopted containment measures to limit the spread of the virus. Urban green spaces (UGSs) were included among the non-essential activities and were consequently closed during the lockdown periods in some countries. This study analysed tweets posted by users to understand the citizens' perception and sentiment in relation to the closure of UGS in Italy. Results revealed that people felt a strong deprivation feeling in relation to the restrictions imposed on UGS access, which limited the number of spaces for supporting mental and physical wellbeing of citizens. Users from urban areas were more affected by the lockdowns and more willing to share thoughts on social media, demonstrating a strong emotionality. Furthermore, findings show that users seemed concerned about their children's health, expressing awareness about the benefits of being in contact with nature. UGS is able to provide services to citizens, and close-to-home parks are fundamental for the community, in particular during a health emergency. The implementation of urban design, which includes green areas to support health and environment challenges, should be addressed by policy-makers to create opportunities for a green and resilient recovery of cities, and prepare for future emergencies.

Looking for “fNIRS Signature” in Autism Spectrum: A Systematic Review Starting From Preschoolers

Accumulating evidence suggests that functional Near-Infrared Spectroscopy (fNIRS) can provide an essential bridge between our current understanding of neural circuit organization and cortical activity in the developing brain. Indeed, fNIRS allows studying brain functions through the measurement of neurovascular coupling that links neural activity to subsequent changes in cerebral blood flow and hemoglobin oxygenation levels. While the literature offers a multitude of fNIRS applications to typical development, only recently this tool has been extended to the study of neurodevelopmental disorders (NDDs). The exponential rise of scientific publications on this topic during the last years reflects the interest to identify a “fNIRS signature” as a biomarker of high translational value to support both early clinical diagnosis and treatment outcome. The purpose of this systematic review is to describe the updating clinical applications of fNIRS in NDDs, with a specific focus on preschool population. Starting from this rationale, a systematic search was conducted for relevant studies in different scientific databases (Pubmed, Scopus, and Web of Science) resulting in 13 published articles. In these studies, fNIRS was applied in individuals with Autism Spectrum Disorder (ASD) or infants at high risk of developing ASD. Both functional connectivity in resting-state conditions and task-evoked brain activation using multiple experimental paradigms were used in the selected investigations, suggesting that fNIRS might be considered a promising method for identifying early quantitative biomarkers in the autism field.

NLRP3 is involved in long bone edification and the maturation of osteogenic cells

Overexpression of the nucleotide-binding leucine-rich repeat protein 3 (NLRP3) inflammasome in chronic auto-immune diseases leads to skeletal anomalies, with severe osteopenia due to the activation of osteoclasts. Reproducing this phenotype in Nlrp3 knock-in mice has provided insights into the role of NLRP3 in bone metabolism. We studied the role of NLRP3 in physiological bone development using a complete Nlrp3 knock-out mouse model. We found impaired skeletal development in Nlrp3-/- mice, resulting in a shorter stature than that of Nlrp3+/+  mice. These growth defects were associated with altered femur bone growth, characterized by a deficient growth plate and an osteopenic profile of the trabeculae. No differences in osteoclast recruitment or activity were observed. Instead, Nlrp3-/- femurs showed a less mineralized matrix in the trabeculae than those of Nlrp3+/+  mice, as well as less bone sialoprotein (BSP) expressing hypertrophic chondrocytes. In vitro, primary osteoblasts lacking NLRP3 expression showed defective mineralization, together with the downregulation of BSP expression. Finally, follow-up by micro-CT highlighted the role of NLPR3 in bone growth, occurring early in living mice, as the osteopenic phenotype diminishes over time. Overall, our data suggest that NLRP3 is involved in bone edification via the regulation of hypertrophic chondrocyte maturation and osteoblast activity. Furthermore, the defect appeared to be transitory, as the skeleton recovered with aging.

Building an Open Source Classifier for the Neonatal EEG Background: A Systematic Feature-Based Approach From Expert Scoring to Clinical Visualization

Neonatal brain monitoring in the neonatal intensive care units (NICU) requires a continuous review of the spontaneous cortical activity, i.e., the electroencephalograph (EEG) background activity. This needs development of bedside methods for an automated assessment of the EEG background activity. In this paper, we present development of the key components of a neonatal EEG background classifier, starting from the visual background scoring to classifier design, and finally to possible bedside visualization of the classifier results. A dataset with 13,200 5-minute EEG epochs (8-16 channels) from 27 infants with birth asphyxia was used for classifier training after scoring by two independent experts. We tested three classifier designs based on 98 computational features, and their performance was assessed with respect to scoring system, pre- and post-processing of labels and outputs, choice of channels, and visualization in monitor displays. The optimal solution achieved an overall classification accuracy of 97% with a range across subjects of 81-100%. We identified a set of 23 features that make the classifier highly robust to the choice of channels and missing data due to artefact rejection. Our results showed that an automated bedside classifier of EEG background is achievable, and we publish the full classifier algorithm to allow further clinical replication and validation studies.

Towards multimodal brain monitoring in asphyxiated newborns with amplitude-integrated EEG and simultaneous somatosensory evoked potentials

BACKGROUND

Somatosensory evoked potentials (SEPs) offer an additional bedside tool for outcome prediction after perinatal asphyxia.

AIMS

To assess the reliability of SEPs recorded with bifrontoparietal amplitude-integrated electroencephalography (aEEG) brain monitoring setup for outcome prediction in asphyxiated newborns undergoing therapeutic hypothermia.

STUDY DESIGN

Retrospective observational single-center study.

SUBJECTS

27 consecutive asphyxiated full- or near-term newborns (25 under hypothermia) that underwent median nerve aEEG-SEPs as part of their clinical evaluation at the neonatal intensive care unit of Helsinki University Hospital.

OUTCOME MEASURES

aEEG-SEP classification (present, absent or unreliable) was compared to classification of SEPs recorded with a full EEG montage (EEG-SEP), and outcome determined from medical records at approximately 12-months-age. Unfavorable outcome included death, cerebral palsy, or severe epilepsy.

RESULTS

The aEEG-SEP and EEG-SEP classifications were concordant in 21 of the 22 newborns with both recordings available. All five newborns with bilaterally absent aEEG-SEPs had absent EEG-SEPs and the four with outcome information available had an unfavorable outcome (one was lost to follow-up). Of the newborns with aEEG-SEPs present, all with follow-up exams available had bilaterally present EEG-SEPs and a favorable outcome (one was lost to follow-up). One newborn with unilaterally absent aEEG-SEP at 25 h of age had bilaterally present EEG-SEPs on the next day, and a favorable outcome.

CONCLUSIONS

aEEG-SEPs recorded during therapeutic hypothermia on the first postnatal days are reliable for assessing brain injury severity. Adding SEP into routine aEEG brain monitoring offers an additional tool for very early outcome prediction after birth asphyxia.

Measuring Cot-Side the Effects of Parenteral Nutrition on Preterm Cortical Function

Early nutritional compromise after preterm birth is shown to affect long-term neurodevelopment, however, there has been a lack of early functional measures of nutritional effects. Recent progress in computational electroencephalography (EEG) analysis has provided means to measure the early maturation of cortical activity. Our study aimed to explore whether computational metrics of early sequential EEG recordings could reflect early nutritional care measured by energy and macronutrient intake in the first week of life. A higher energy or macronutrient intake was assumed to associate with improved development of the cortical activity. We analyzed multichannel EEG recorded at 32 weeks (32.4 ± 0.7) and 36 weeks (36.6 ± 0.9) of postmenstrual age in a cohort of 28 preterm infants born before 32 weeks of postmenstrual age (range: 24.3–32 weeks). We computed several quantitative EEG measures from epochs of quiet sleep (QS): (i) spectral power; (ii) continuity; (iii) interhemispheric synchrony, as well as (iv) the recently developed estimate of maturational age. Parenteral nutritional intake from day 1 to day 7 was monitored and clinical factors collected. Lower calories and carbohydrates were found to correlate with a higher reduction of spectral amplitude in the delta band. Lower protein amount associated with higher discontinuity. Both higher proteins and lipids intake correlated with a more developmental increase in interhemispheric synchrony as well as with better progress in the estimate of EEG maturational age (EMA). Our study shows that early nutritional balance after preterm birth may influence subsequent maturation of brain activity in a way that can be observed with several intuitively reasoned and transparent computational EEG metrics. Such measures could become early functional biomarkers that hold promise for benchmarking in the future development of therapeutic interventions.

Movement analysis in early infancy: Towards a motion biomarker of age

BACKGROUND

Early motor development is characterized by progressive changes in general movements paralleled by a gradual organization of the four limbs' repertoire towards the midline, as shown by computerised movement analysis.

AIMS

Our aim was to test the performance of quantitative computerised kinematic indexes as predictors of post-term age in an independent cohort of typically developing subjects at fidgety age, tested cross-sectionally.

SUBJECTS

We selected twelve low risk term infants, who were video recorded between 9 and 20 weeks (fidgety age) during one spontaneous movements session.

STUDY DESIGN

We correlated post-term age with I)indexes of coordination including interlimb correlation of velocity and position, II)indexes of distance, including interlimb and limb-to- ground, both expressed as linear distance and as probability of midline limbs position III)indexes of global movement quality by calculating Hjorth's activity, mobility and complexity parameters. All indexes were calculated for both upper and lower limbs.

RESULTS

Significant positive correlations were found between post-term age and indexes of distance, and probability of occurrence of upper-limb antigravity patterns, and with both indexes of global movement quality. By combining linear and non-linear parameters related to the upper limb kinematics, we determined individual post-term age with a mean error of <1 week (5.2 days). No correlations were found between age and indexes of coordination.

CONCLUSIONS

Quantitative computerised analysis of upper-limb movements is a promising predictor of post-term age in typically developing subjects at fidgety age.

Cerebral Palsy: Early Markers of Clinical Phenotype and Functional Outcome

The Prechtl General Movement Assessment (GMA) has become a cornerstone assessment in early identification of cerebral palsy (CP), particularly during the fidgety movement period at 3-5 months of age. Additionally, assessment of motor repertoire, such as antigravity movements and postural patterns, which form the Motor Optimality Score (MOS), may provide insight into an infant's later motor function. This study aimed to identify early specific markers for ambulation, gross motor function (using the Gross Motor Function Classification System, GMFCS), topography (unilateral, bilateral), and type (spastic, dyskinetic, ataxic, and hypotonic) of CP in a large worldwide cohort of 468 infants. We found that 95% of children with CP did not have fidgety movements, with 100% having non-optimal MOS. GMFCS level was strongly correlated to MOS. An MOS > 14 was most likely associated with GMFCS outcomes I or II, whereas GMFCS outcomes IV or V were hardly ever associated with an MOS > 8. A number of different movement patterns were associated with more severe functional impairment (GMFCS III-V), including atypical arching and persistent cramped-synchronized movements. Asymmetrical segmental movements were strongly associated with unilateral CP. Circular arm movements were associated with dyskinetic CP. This study demonstrated that use of the MOS contributes to understanding later CP prognosis, including early markers for type and severity.

Automated pose estimation captures key aspects of General Movements at eight to 17 weeks from conventional videos

AIM

General movement assessment requires substantial expertise for accurate visual interpretation. Our aim was to evaluate an automated pose estimation method, using conventional video records, to see if it could capture infant movements using objective biomarkers.

METHODS

We selected archived videos from 21 infants aged eight to 17 weeks who had taken part in studies at the IRCCS Fondazione Stella Maris (Italy), from 2011 to 2017. Of these, 14 presented with typical low-risk movements, while seven presented with atypical movements and were later diagnosed with cerebral palsy. Skeleton videos were produced using a computational pose estimation model adapted for infants and these were blindly assessed to see whether they contained the information needed for classification by human experts. Movements of skeletal key points were analysed using kinematic metrics to provide a biomarker to distinguish between groups.

RESULTS

The visual assessments of the skeleton videos were very accurate, with Cohen's K of 0.90 when compared with the classification of conventional videos. Quantitative analysis showed that arm movements were more variable in infants with typical movements.

CONCLUSION

It was possible to extract automated estimation of movement patterns from conventional video records and convert them to skeleton footage. This could allow quantitative analysis of existing footage.

Evaluation of SEPs in asphyxiated newborns using a 4-electrode aEEG brain monitoring set-up

•

Neonatal SEPs can be reliably detected using the 4-electrode aEEG monitoring setup.

•

SEP is discernible in most fullterm newborns with 300 averages.

•

Recording SEPs jointly with aEEG facilitates SEP assessment after birth asphyxia.

Objective

To evaluate the reliability of recording cortical somatosensory evoked potentials (SEPs) in asphyxiated newborns using the 4-electrode setup applied in routine long-term amplitude-integrated EEG (aEEG) brain monitoring and to assess the number of averages needed for reliably detecting the cortical responses.

Methods

We evaluated median nerve SEPs in 50 asphyxiated full-term newborns. The SEP interpretation (present or absent) from the original recordings with 21-electrodes and approximately 600 trials served as the reference. This was compared to SEP classification (absent, present, or unreliable) based on a reduced (300 or 150) number of averages, and to classification based on only four electrodes (F3, P3, F4, P4).

Results

Compared to the original classification, cortical SEPs were uniformly interpreted as present or absent in all 50 newborns with the 4-electrode setup and 600 averages. Reducing number of averages to 300 still resulted in correct SEP interpretation in 49/50 newborns with 21-electrode setup, and 46/50 newborns with 4-electrode setup.

Conclusions

Evaluation of early cortical neonatal SEPs is reliable from the 4-electrode setup commonly used in aEEG monitoring. SEP is discernible in most newborns with 300 averages.

Significance

Adding SEP into routine aEEG monitoring offers an additional tool for early neonatal neurophysiological evaluation.

Evoked potentials recorded during routine EEG predict outcome after perinatal asphyxia

OBJECTIVE

To evaluate the added value of somatosensory (SEPs) and visual evoked potentials (VEPs) recorded simultaneously with routine EEG in early outcome prediction of newborns with hypoxic-ischemic encephalopathy under modern intensive care.

METHODS

We simultaneously recorded multichannel EEG, median nerve SEPs, and flash VEPs during the first few postnatal days in 50 term newborns with hypoxic-ischemic encephalopathy. EEG background was scored into five grades and the worst two grades were considered to indicate poor cerebral recovery. Evoked potentials were classified as absent or present. Clinical outcome was determined from the medical records at a median age of 21months. Unfavorable outcome included cerebral palsy, severe mental retardation, severe epilepsy, or death.

RESULTS

The accuracy of outcome prediction was 98% with SEPs compared to 90% with EEG. EEG alone always predicted unfavorable outcome when it was inactive (n=9), and favorable outcome when it was normal or only mildly abnormal (n=17). However, newborns with moderate or severe EEG background abnormality could have either favorable or unfavorable outcome, which was correctly predicted by SEP in all but one newborn (accuracy in this subgroup 96%). Absent VEPs were always associated with an inactive EEG, and an unfavorable outcome. However, presence of VEPs did not guarantee a favorable outcome.

CONCLUSIONS

SEPs accurately predict clinical outcomes in newborns with hypoxic-ischemic encephalopathy and improve the EEG-based prediction particularly in those newborns with severely or moderately abnormal EEG findings.

SIGNIFICANCE

SEPs should be added to routine EEG recordings for early bedside assessment of newborns with hypoxic-ischemic encephalopathy.

Luteal activity and effect of dietary energy restriction on follicular development in lactating cows

The aim of this research has been to evaluate the presence of anomalies in the ovarian cycle activity during postpartum and to verify whether 72-hr dietary fasting during the dominance phase, the phase before ovulation, might modify the ovarian follicle population. The presence of anomalies in ovarian cycle activity has been evaluated in 30 Italian Friesian cows starting from 20 days postpartum until 211 days of lactation. Long oestrus and brief dioestrus or scarce luteal activity have been the main anomalies found through measuring progesterone concentrations in the whey. Until 100 days of lactation, the BCS values of the problematic animals have been significantly lower than those in animals with normal ovarian activity. After 100 days of lactation, the ovarian anomalies continued to appear despite the fact that all the animals have reached comparable BCS values. Starting from the results of this trial, the effect of 72-hr dietary fasting on dominant follicles has been studied in six cows. Ultrasonography revealed that the diameter of the follicles at 71 days postpartum has been significantly lower than at 181 days. A 72-hr dietary restriction at 101 and 211 days postpartum did not affect the size of the dominant follicle. However, at 101 days postpartum, half of the animals presented follicular cysts. The effect of fasting differed if the animal has been in early postpartum or 211 days of lactation. Further researches are necessary to understand how different metabolic conditions can modify the follicular population but on the other hand the study shows the utility for farmers and field veterinarians of monitoring the resumption of the ovarian cycle postpartum through the whey progesterone concentrations.

An aqueous one-pot route to gold/quantum rod heterostructured nanoparticles functionalized with DNA

We report an original approach exploiting the photoelectrochemical properties of quantum rods and the versatility of Au(I) organometallic chemistry to control DNA surface grafting. This one-pot aqueous approach provides Janus biofunctionalized nanoparticles, the assembly of which should results in the emergence of synergistic properties.

Synthesis and enzymatic photo-activity of an O2 tolerant hydrogenase-CdSe@CdS quantum rod bioconjugate

This communication reports on the preparation of stable and photo-active nano-heterostructures composed of O2 tolerant [NiFe] hydrogenase extracted from the Aquifex aeolicus bacterium grafted onto hydrophilic CdSe/CdS quantum rods in view of the development of H2/O2 biofuel cells. The resulting complex is efficient towards H2 oxidation, displays good stability and new photosensitive properties.

Brain representation of action observation in human infants

Imitative learning has long been established as extremely important for early development. However, neural mechanisms involved in early imitative behaviours are still areas of active research. Neurophysiological and brain-imaging studies have been recently performed that provide initial evidence of brain activation associated with action observation in the first months of life. In this review we examine all studies exploring the effects of action observation on brain function assessed by means of non-invasive brain-mapping techniques. Seventeen papers were selected as a result of our literature search. The strongest evidence for a neural signature of action observation comes from studies exploring the desynchronization of the μ-rhythm, which was reported for both occluded and visible goal-directed grasp, and was correlated with the totality of the infant's own action experience. The effects of action observation were reported on event-related potentials (ERPs) or near infrared spectroscopy. Taken together, these studies suggest that, in early infancy, a direct visual-motor matching process is already detectable as early as 6 months, suggesting a matching between action perception and execution already in infancy. If confirmed by future studies, these findings will shed light on the mechanisms of early motor development and imitation, and will be key to informing novel rehabilitation strategies in infants with congenital brain damage.

The first 1000 days of the autistic brain: a systematic review of diffusion imaging studies

There is overwhelming evidence that autism spectrum disorder (ASD) is related to altered brain connectivity. While these alterations are starting to be well characterized in subjects where the clinical picture is fully expressed, less is known on their earlier developmental course. In the present study we systematically reviewed current knowledge on structural connectivity in ASD infants and toddlers. We searched PubMed and Medline databases for all English language papers, published from year 2000, exploring structural connectivity in populations of infants and toddlers whose mean age was below 30 months. Of the 264 papers extracted, four were found to be eligible and were reviewed. Three of the four selected studies reported higher fractional anisotropy values in subjects with ASD compared to controls within commissural fibers, projections fibers, and association fibers, suggesting brain hyper-connectivity in the earliest phases of the disorder. Similar conclusions emerged from the other diffusion parameters assessed. These findings are reversed to what is generally found in studies exploring older patient groups and suggest a developmental course characterized by a shift toward hypo-connectivity starting at a time between two and four years of age.

Replacement of CTAB with peptidic ligands at the surface of gold nanorods and their self-assembling properties

Herein, we describe the self-assembling of gold nanorods (GNRs) induced during the ligand exchange at their surface. An exchange reaction between tricysteine PEGylated peptidic ligands and cetyltrimethylammonium bromide (CTAB)-protected gold nanorods is conducted. We demonstrated that the terminal group charge (positively or negatively charged) and the hydrophobicity of the peptidic ligands (bearing or not an undecanoyl chain) strongly affects the self-organization of the GNRs occurring in solution. Adjusting the amount of short PEGylated peptides causes a self-organization of the gold nanorods in solution, resulting in a red- or blue-shift of the plasmon bands. The decrease of their surface charge and the self-assembling in solution were first shown by zetametry, by Dynamic Light Scattering and UV-spectroscopy. Thanks to Small Angle X-ray Scattering experiments and Transmission Electron Microscopy images, the self-organization of the nanorods in solution was clearly demonstrated and correlated to the spectroscopic change in absorbance. Conversely, in the case of longer PEGylated peptidic ligands including an undecanoyl chain, the GNRs are particularly stable against aggregation for several days after purification. By controlled drying on a substrate, we showed their ability to self-organize into well-defined ordered structures making them very attractive as building blocks to design optical materials.

The effect of an acute energy deficit on the hormone profile of dominant follicles in dairy cows

The effect of an acute energy deficit on the hormone balance of dominant follicles was studied in six normally-cycling, high-yielding Italian Friesian cows at 60 and 90 days after calving. At 60 days after calving, the cows, which had been fed according to their maintenance and production requirements, were synchronized and follicular fluid was collected from the dominant follicles under ultrasound guidance. At 90 days after calving, the same protocol was used on the same cows, which had been subjected to an acute dietary restriction since the day of the second prostaglandin treatment for synchronization. At the follicular level, the dietary restriction caused a significant reduction (P < 0.05) in the concentration of estradiol-17beta and a significant increase (P < 0.05) in NEFA. There were no significant differences in follicular diameter, follicular concentrations of progesterone, and Insulin-like Growth Factor-I (IGF-I). The amount of IGFBP2 and IGFBP3 in follicular fluid increased. The results suggest that an acute dietary restriction induces substantial changes at the dominant follicle level, despite the fact that the recruitment and selection phase occurred before the cows' diet was restricted.

Effect of insemination time of frozen semen on incidence of uterine fluid in mares

Ninety five mares were inseminated with frozen semen either within 12 h before ovulation or within 8 h after ovulation. The effect of preovulatory versus postovulatory insemination (AI) on the subsequent detection of uterine fluid was studied. The overall pregnancy rate was 43% and this was not significantly influenced by preovulatory or postovulatory insemination. When mares were first examined 12 h after AI, 18 of 52 mares (35%) had accumulated uterine fluid. However, when mares were first examined 18 to 24 h after AI, only 6 of 43 mares (14%) had uterine fluid. Presence of intrauterine fluid significantly lowered pregnancy rates. Timing of insemination did not affect incidence of uterine fluid. Serum concentrations of estrogen and progesterone at time of insemination did not influence uterine clearance or pregnancy rates, but both hormones were higher at preovulatory than at postovulatory inseminations. We concluded that there was no evidence that postovulatory inseminations would predispose mares to persistence of uterine fluid after AI.

Mathematical Models of Picosecond Laser Keratomileusis for High Myopia

PURPOSE

Picosecond laser keratomileusis (PLK) is a refractive surgical procedure in which an intrastromal lenticle is created using the Nd:YLF picosecond laser and removed by lifting the anterior flap in the cornea. The purpose of this study was to assess the predictability of picosecond laser keratomileusis for high myopia.

METHODS

The results from a recent clinical series of non-sighted patients who had undergone picosecond laser keratomileusis with the Nd:YLF picosecond laser were retrospectively simulated with two mathematical models. In one model, the change in corneal curvature resulting from the collapse of a lenticular intrastromal cavity was predicted from a geometric analysis. A second model was developed using the finite element method. The results of both predictive models were compared to the clinical results at 1 and 6 months following surgery.

RESULTS

An average -13.30 D of flattening (range, -6.80 to -20.50 D) was measured at 6 months. The geometric model predicted an average correction of -23.10 D (range, -18.00 to -34.00 D), whereas the finite element model predicted an average curvature change of -17.40 D (range, -14.50 to -22.50 D). An average decrease in central pachymetry of 91 microm was measured at 6 months, as compared to a predicted decrease in thickness of 112 microm.

CONCLUSIONS

The outcome of picosecond laser keratomileusis for high myopia predicted using a finite element based model shows greater change in the corneal curvature and corneal thickness compared to clinical results. The relatively thick lenticules that are removed for high myopia cause considerable deformational changes in the cornea, which preclude the use of a purely geometric/optical approach for predicting the resultant corneal curvature changes.

An N-terminal EF hand-like motif modulates ion transport by Pmr1, the yeast Golgi Ca(2+)/Mn(2+)-ATPase

Pmr1, a novel member of the family of P-type ATPases, localizes to the Golgi compartment in yeast where it provides Ca(2+) and Mn(2+) for a variety of normal secretory processes. We have previously characterized Ca(2+) transport in isolated Golgi vesicles, and described an expression system for the analysis of Pmr1 mutants in a yeast strain devoid of background Ca(2+) pump activity [Sorin, A., Rosas, G., and Rao, R. (1997) J. Biol. Chem. 272, 9895-9901]. Here we show, using recombinant bacterial fusions, that an N-terminal EF hand-like motif in Pmr1 binds Ca(2+). Increasing disruptions of this motif led to progressive loss of pump function; thus, the single point mutations D51A and D53A retained pump activity but with drastic reductions in the affinity for Ca(2+) transport, while the double mutant was largely unable to exit the endoplasmic reticulum. In-frame deletions of the Ca(2+)-binding motif resulted in complete loss of function. Interestingly, the single point mutations conferred differential affinities for transport of Ca(2+) and Mn(2+) ions. Further, the proteolytic stability of the catalytic ATP-binding domain is altered by the N-terminal mutations, suggesting an interaction between these two regions of polypeptide. These studies implicate the N-terminal domain of Pmr1 in the modulation of ion transport, and may help elucidate the role of N-terminal metal-binding sites of Cu(2+)-ATPases, defective in Wilson and Menkes disease.

Induction of vacuolar Ca2+-ATPase and H+/Ca2+ exchange activity in yeast mutants lacking Pmr1, the Golgi Ca2+-ATPase

We have analyzed Ca2+ transport activity in defined subcellular fractions of an isogenic set of wild-type and mutant yeast. The results, together with measurements of polypeptide expression levels and promoter::reporter gene activity, show that the Golgi Ca2+-ATPase, Pmr1, is the major Ca2+ pump under normal growth conditions. In the absence of Pmr1, we show a massive, calcineurin-dependent compensatory induction of the vacuolar Ca2+-ATPase, Pmc1. In addition, H+/Ca2+ exchange activity, that may be distinct from the vacuolar exchanger Vcx1, is also increased.

Clinical analysis of the neodymium:YLF picosecond laser as a microkeratome for laser in situ keratomileusis. Partially Sighted Eye Study

PURPOSE

To evaluate the use of a picosecond neodymium:YLF (Nd:YLF) laser as a nonmechanical intrastromal microkeratome.

SETTING

Universita Cattolica del Sacro Cuore, Rome, Italy.

METHODS

An intrastromal spiral disc pattern of picosecond laser pulses was used to create a corneal flap for laser in situ keratomileusis (LASIK) in 14 partially sighted eyes.

RESULTS

Flaps with a 6.0 mm diameter and 180 to 200 microns depth were successfully created in most cases. The underlying stroma was treated with a Lambda Physik excimer laser using a 3.5 to 4.5 mm optical zone. Patients were divided into 3 groups for target corrections of 5.0, 10.0, and 15.0 diopters of myopia. Good corneal clarity and refractive undercorrection were recorded in each group 6 months postoperatively. The undercorrection was due in part to the limited optical zone of the laser's delivery system. Some flap decentration was noted.

CONCLUSION

This pilot study indicates that the Nd:YLF picosecond laser may be clinically applied for creating corneal flaps for LASIK. Further refinements of the laser delivery system will include enlargement of the flap diameter and improvements in flap centration. The use of a femtosecond laser may expand the capabilities and precision of this technology.

The Picosecond Laser for Nonmechanical Laser in situ Keratomileusis

PURPOSE

To introduce the clinical use of the Nd:YLF picosecond laser as a nonmechanical microkeratome.

METHODS

A commercially available Nd:YLF picosecond laser (25 microJ/pulse, 30 psec, 1053 nm) was used to deliver intrastromal pulses of focused high power laser light to generate a flap for laser in situ keratomileusis (LASIK) and perform picosecond laser keratomileusis (PLK) in two partially sighted patients with high myopia.

RESULTS

Case #1: A 6 mm, 150 microns flap for LASIK was successfully created and the underlying stroma treated with an excimer laser for a target correction of -15.00 D of myopia. Good corneal clarity and a refractive change of -14.00 D was recorded 2 months postoperatively. Case #2: Both eyes of a high myope (-22.00 D right eye, -21.50 D left eye) underwent picosecond laser keratomileusis, removing a 3.2 mm diameter lenticule of 120 microns thickness under a 200 microns flap. Postoperative refraction was -2.00 D at 7 months in the right eye and -0.75 D at 2 months in the left eye with improvement of spectacle-corrected visual acuity from 20/200 to 20/70 in each eye.

CONCLUSION

The Nd:YLF picosecond laser can be safely used in creating a corneal flap for LASIK and in performing picosecond laser keratomileusis for high myopia. Future refinements in the laser will include a larger flap diameter and femtosecond pulsing capability.

Intrastromal Photorefractive Keratectomy for Myopia by Nd:YLF Picosecond Laser

BACKGROUND

An intrastromal photorefractive keratectomy (ISPRK) by Nd:YLF Picoseconds Laser has been performed on 17 eyes with corrected visual acuity of 20/200 or worse. The purpose of this study was to study the safety and effectiveness of ISPRK using different laser parameters.

METHODS

The Neodymiun Yttrium Lithium Fluoride laser system (Nd:YLF) was used to perform the myopic treatment. We studied the effect of pattern depth, the numbers of patterns, the thickness of a single spiral pattern, the distance between two patterns along Z axis, the pattern curvature perpendicular to the Z axis, the energy, the spatial density, and the repetition frequency of the laser pulse.

RESULTS

The laser treatment was completed in 12 patients. In the first group at 180 days postoperatively we did not find corneal opacities, anterior chamber or lens opacities. Pupil diameter and reactivity, endothelial cell density, and IOP were normal. Pachymetry showed an average reduction of the central corneal thickness of 99 microns (+/- 14.7 SD). Topography showed an average reduction of the corneal dioptric power of 2 D (+/- 0.4 SD). In the second group at 120 days postoperatively findings were similar. Pachymetry showed an average reduction of the central corneal thickness of 118.5 mu (+/- 12.5 SD). Topography showed an average reduction of the corneal dioptric power of 2.4D (+/- 0.9 SD).

CONCLUSIONS

It is possible to change the corneal power by reducing the corneal thickness with the Nd:YLF laser but the predictability of the result is unknown. Because Bowman's layer is intact, there is no scarring or haze.

Effect of HIV-1 peptide presentation on the affinity constants of two monoclonal antibodies determined by BIAcore technology

We studied two monoclonal antibodies (MAbs 9-11 and 41-1) which are specific for dominant and conserved epitopes located on HIV-1 transmembrane Gp41. These MAbs recognize both Gp41 and a synthetic HIV-1 envelope peptide (39GC) which is a fragment of Gp41. The interactions between MAbs 9-11 and 41-1 and 39GC either coupled to a sensor chip or to alkaline phosphatase were investigated using BIAcore technology. The association and dissociation rate constants as well as the affinity constants were determined. BIAcore technology allows real-time determination of the interaction between two molecules without the need for any labeling, neither isotopic nor enzymatic. The peptide 39GC was immobilized by coupling to dextran on the BIAcore biosensor through a disulfide bond with a cysteine residue added to the N-terminus of the synthetic peptide. The two native cysteine residues located in the loop of Gp41 were protected by ethylcarbamoyl residues (CONHC2H5); this chemical modification prevented the formation of the S-S bridge and in particular the internal loop. We specifically studied the interaction between the MAbs and either the protected peptide or the peptide whose cysteine residues had been deprotected in situ by alkaline treatment. The results showed that MAb 41-1 recognized 39GC either protected (Ka = 7.6 x 10(6) M-1) or unprotected (Ka = 1.48 x 10(8) M-1), whereas MAb 9-11 recognized only the unprotected form (Ka = 2.18 x 10(8) M-1). Our results suggest that the epitope MAb 9-11 is directed against a part of the peptide sequence which includes the two native cysteines. The difference in affinity observed for MAb 41-1 between the protected and the unprotected forms of 39GC was found to be due to a lower rate of dissociation for unprotected 39GC; these results illustrate the importance of peptide conformation on antibody recognition and might be explained by a conformational change due to reconstitution of the internal loop following deprotection of the thiol groups. MAbs 9-11 and 41-1 also recognized 39GC conjugated to alkaline phosphatase and deprotected. We observed a difference between the rate constants for MAb 41-1 binding to free peptide and its binding to the peptide-enzyme conjugate which might be due to changes in peptide flexibility. In contrast, the rate constants of MAb 9-11 were the same in both experiments, suggesting that the rigidity of the internal loop prevents changes in 9-11 epitope conformation.

Osteo-odonto-keratoprosthesis. Description of surgical technique with results in 85 patients

Osteo-odonto-keratoprosthesis is a technique designed for patients with severe corneal opacification who would be at high risk of graft rejection should donor tissue transplantation be performed. Because of the isolation of the prosthetic implant from the tissues that the technique provides, the authors are of the opinion that it is the only viable option in such patients. The visual outcome and complications of the procedure in a series of 85 cases are presented.

Strampelli's osteo-odonto-keratoprosthesis. Clinical and histological long-term features of three prostheses

The histological features are reported of osteo-odonto-acrylic laminae removed from three patients who for differing underlying causes received Strampelli's osteo-odonto-keratoprostheses (OOK) 20, 16, and 12 years previously. It appears that preservation of the alveolar-dental ligament plays a definitive role in the maintenance of the prosthesis. If this tissue undergoes necrosis as a consequence of an inflammatory disease the implanted material is eventually lost. However when no such event occurs the OOK is well preserved and well tolerated even 20 years after implantation.