Perinatal arterial ischemic stroke: how informative is the placenta?

Neuroplacentology is an expanding field of interest that addresses the placental influence on fetal and neonatal brain lesions and on further neurodevelopment. The objective of this study was to clarify the link between placental pathology and perinatal arterial ischemic stroke (PAIS). Prior publications have reported different types of perinatal stroke with diverse methodologies precluding firm conclusions. We report here the histological placental findings in a series of 16 neonates with radiologically confirmed PAIS. Findings were grouped into 3 categories of lesions: (1) inflammation, (2) placental and fetal hypoxic lesions, and (3) placentas with a high birthweight/placenta weight ratio. Matched control placentas were compared to the pathological placentas when feasible. The eight term singleton placentas were compared to a series of 20 placentas from a highly controlled amniotic membrane donation program; in three twin pregnancies, the placental portions from the affected twin and unaffected co-twin were compared. Slightly more than half (9/16, 56%) had histopathological features belonging to more than one category, a feature shared by the singleton control placentas (13/20, 65%). More severe and extensive lesions were however observed in the pathological placentas. One case occurring in the context of SARS-CoV-2 placentitis further expands the spectrum of COVID-related perinatal disease. Our study supports the assumption that PAIS can result from various combinations and interplay of maternal and fetal factors and confirms the value of placenta examination. Yet, placental findings must be interpreted with caution given their prevalence in well-designed controls.

Ultrafast pulse shaping modulates perceived visual brightness in living animals

Vision is usually assumed to be sensitive to the light intensity and spectrum but not to its spectral phase. However, experiments performed on retinal proteins in solution showed that the first step of vision consists in an ultrafast photoisomerization that can be coherently controlled by shaping the phase of femtosecond laser pulses, especially in the multiphoton interaction regime. The link between these experiments in solution and the biological process allowing vision was not demonstrated. Here, we measure the electric signals fired from the retina of living mice upon femtosecond multipulse and single-pulse light stimulation. Our results show that the electrophysiological signaling is sensitive to the manipulation of the light excitation on a femtosecond time scale. The mechanism relies on multiple interactions with the light pulses close to the conical intersection, like pump-dump (photoisomerization interruption) and pump-repump (reverse isomerization) processes. This interpretation is supported both experimentally and by dynamics simulations.

Locking compression plate fixation in humeral shaft fractures: A comparative study to literature conservative treatment

INTRODUCTION

Humeral shaft fractures represent about 3% of all fractures. While there are several treatment options for this type of fractures, there is no evidence in literature showing which is the best one. This study aims at analysing the outcomes for patients with humeral shaft fractures treated with Locking Compression Plate (LCP) fixation in our hospital and comparing them with the outcome for patients conservatively treated (according to data from Pubmed),in order to determine the best treatment option.

MATERIALS AND METHODS

We treated surgically 220 humeral shaft fractures in our department from February 2005 to March 2012. Seventy-three of them met all the inclusion criteria for this study. All fractures were then classified according to the AO classification. The follow-up considered the radiographic healing of the fracture. All patients were treated with plate fixation (LCP - DePuySynthes Co). At the end of the four-year follow-up, the function was evaluated by means of the DASH score. A systematic review of the literature of the last 20 years was performed on MEDLINE (PubMed).

RESULTS

We had 2 infections and 8 patients had postoperative nerve palsy which recovered in average time of 6.7 months. In addition, 4 fractures (5.48%) didn't heal within 6 months and they were considered as nonunions and healed after a second surgery. One of these 4 nonunions was infected. The mean DASH score was 18.24±19.18. No malunions were found. We identified 13 studies that were eligible for our systematic review. The mean non-union rate found was 17% in 2517 fractures with a follow-up that ranging from 67% to 100% of patients and a primary radial nerve palsy ranging from 0 to 115 patients. Malalignment rate ranged from 12.7 to 42%.

CONCLUSIONS

After taking into account both the conservative and the surgical treatment, for humeral shaft fractures we suggest the operative treatment, because the patient's function of the upper limb recovers quickly in the immediate postoperative period and the incidence of malunions may be avoided.

To fix or not to fix? The role of fibular fixation in distal shaft fractures of the leg

BACKGROUND

The role of stabilisation of the fibula in distal two-bone fractures of the leg is controversial. Some studies indicate the need for fibular stabilisation in 43 AO fractures, but few studies consider the role of the fibula in 42 AO fractures. The aim of the current paper is to explain the role of stabilisation of the fibula in 42 AO fractures, correlating the rates of healing and non-union between patients with and without fibula fixation.

MATERIALS AND METHODS

A total of 60 patients with 42 AO (distal) shaft fracture of the tibia with associated fracture of the fibula were selected. Patients were divided into two groups according to whether or not the fibula was fixed: Group I (n=26) comprised patients who had their fibula fixed while Group II (n=34) comprised patients who did not. The fibular fracture was classified according to the AO and related to the level of the tibial fracture. Other parameters examined were the union rate of the two groups correlated to the fracture pattern and position of the fibular fracture; the demographic data, such as age and gender; the presence of an open fracture, and the type of tibial fixation device used (nail or plate).

RESULTS

None of the parameters considered (open injury, AO classification, device used and level of the fibular fracture relative to the tibial) were shown to have an influence on the development of a non-union.

CONCLUSION

This study showed a higher non-union rate when the fracture of the tibia and fibula were at the same level, the tibia was fixed with a bridging plate and the fibula left untouched. For this reason, we recommend fibular fixation in all 42 distal fractures when both fractures lie on the same plane and the tibial fracture is relatively stabilised.

A positive feedback loop between ATOH7 and a Notch effector regulates cell-cycle progression and neurogenesis in the retina

The HES proteins are known Notch effectors and have long been recognized as important in inhibiting neuronal differentiation. However, the roles that they play in the specification of neuronal fate remain largely unknown. Here, we show that in the differentiating retinal epithelium, the proneural protein ATOH7 (ATH5) is required for the activation of the transcription of the Hes5.3 gene before the penultimate mitosis of progenitor cells. We further show that the HES5.3 protein slows down the cell-cycle progression of Atoh7-expressing cells, thereby establishing conditions for Atoh7 to reach a high level of expression in S phase and induce neuronal differentiation prior to the ultimate mitosis. Our study uncovers how a proneural protein recruits a protein known to be a component of the Notch signaling pathway in order to regulate the transition between an initial phase of selection among uncommitted progenitors and a later phase committing the selected progenitors to neuronal differentiation.

Role of the c-Jun N-terminal kinase pathway in retinal excitotoxicity, and neuroprotection by its inhibition

Retinal excitotoxicity is associated with retinal ischemia, and with glaucomatous and traumatic optic neuropathy. The present study investigates the role of c-Jun N-terminal kinase (JNK) activation in NMDA-mediated retinal excitotoxicity and determines whether neuroprotection can be obtained with the JNK pathway inhibitor, D-form of JNK-inhibitor 1 (D-JNKI-1). Young adult rats received intravitreal injections of 20 nmol NMDA, which caused extensive neuronal death in the inner nuclear and ganglion cell layers. This excitotoxicity was associated with strong activation of calpain, as revealed by fodrin cleavage, and of JNK. The cell-permeable peptide D-JNKI-1 was used to inhibit JNK. Within 40 min of its intravitreal injection, FITC-labeled D-JNKI-1 spread through the retinal ganglion cell layer into the inner nuclear layer and interfered with the NMDA-induced phosphorylation of JNK. Injections of unlabeled D-JNKI-1 gave unprecedentedly strong neuroprotection against cell death in both layers, lasting for at least 10 days. The NMDA-induced calpain-specific fodrin cleavage was likewise strongly inhibited by D-JNKI-1. Moreover the electroretinogram was partially preserved by D-JNKI-1. Thus, the JNK pathway is involved in NMDA-mediated retinal excitotoxicity and JNK inhibition by D-JNKI-1 provides strong neuroprotection as shown morphologically, biochemically and physiologically.

Conserved regulatory sequences in Atoh7 mediate non-conserved regulatory responses in retina ontogenesis

The characterisation of interspecies differences in gene regulation is crucial to understanding the molecular basis of phenotypic diversity and evolution. The atonal homologue Atoh7 participates in the ontogenesis of the vertebrate retina. Our study reveals how evolutionarily conserved, non-coding DNA sequences mediate both the conserved and the species-specific transcriptional features of the Atoh7 gene. In the mouse and chick retina, species-related variations in the chromatin-binding profiles of bHLH transcription factors correlate with distinct features of the Atoh7 promoters and underlie variations in the transcriptional rates of the Atoh7 genes. The different expression kinetics of the Atoh7 genes generate differences in the expression patterns of a set of genes that are regulated by Atoh7 in a dose-dependent manner, including those involved in neurite outgrowth and growth cone migration. In summary, we show how highly conserved regulatory elements are put to use in mediating non-conserved functions and creating interspecies neuronal diversity.

Functional study in NSE-Hu-Bcl-2 transgenic mice: a model for retinal diseases starting in Müller cells

In NSE-Hu-Bcl-2 transgenic mice, line 71, retina undergoes early postnatal degeneration linked to the prior death of Müller cells. The purpose of this study was to complete the characterization of this retinal dysfunction by using electroretinographic (ERG) recordings in both scotopic and photopic conditions. Here, we showed that both rod and cone systems were profoundly affected in NSE-Hu-Bcl-2 transgenic mice as soon as 15 postnatal days in accordance with histological study performed previously.

Influence of the diameters of tendon graft and bone tunnel in hamstring ACL reconstruction. A bovine model

In an animal model of Anterior Cruciate Ligament reconstruction by hamstring tendons and 8mm diameter biodegradable interference screws, we aimed to investigate whether pull out forces and failure modes were influenced by changing tendon and bone tunnel diameters. Three groups of 10 calf tibiae each were prepared with 8, 9 and 10mm diameter proximal tunnels fitted respectively with 8, 9 and 10mm diameter tendon grafts. Mean +/- SD pull out force was 607.9 +/- 191.5N in the 8mm group, 494.2 +/- 206.2N in the 9mm group and 530.4 +/- 212.5N in the 10mm group. These differences were not significant at t-test. 8mm specimens failed by tendon rupture, 10mm specimens failed by screw pull out and 9mm specimens failed in both ways. In this ACL reconstruction model, safe pull out forces were achieved by fixing tendon grafts to bone by 8 mm absorbable interference screws regardless of tendon and bone tunnel diameter.

Activity analysis of housekeeping promoters using self-inactivating lentiviral vector delivery into the mouse retina

For most retinal degeneration disorders, no efficient treatment exists to preserve photoreceptors (PRs) and, consequently, to maintain vision. Gene transfer appears to be a promising approach to prevent PR loss. In order to design adequate vectors to target specific retinal cell types, we have analyzed the expression pattern of three different promoters (mouse phosphoglycerate kinase 1 (PGK), elongation factor-1 (EFS), rhodopsin (Rho)) in newborn and adult DBA/2 mice retinas using self-inactivating lentiviral vectors. At 7 days after intraocular injection and in optimal conditions, cell transduction was observed up to 1.5 mm from the injection site. PGK promoter expression was predominant in the retinal pigment epithelium (RPE), especially in adult mice, whereas the EFS promoter allowed a broad expression in the retina. Finally, as expected, the Rho promoter was specifically expressed in PRs. Differences in the cell types transduced and in transduction efficiency were observed between newborn and adult injected eyes emphasizing the importance of such basic studies for further gene therapy approaches as well as for understanding the transcriptional changes during retinal maturation. Thus, for future attempts to slow or rescue retinal degeneration by lentiviral delivery, PGK and EFS are more suitable to control the expression of a supporting secreted factor, PGK being mainly expressed in RPE and EFS in different cell types throughout the entire retina, whereas Rho should allow to specifically deliver the therapeutic gene to PRs.

Cerebrospinal fluid concentrations of atracurium, laudanosine and vecuronium following clinical subarachnoid hemorrhage

BACKGROUND

Neuromuscular blocking agents may exert central nervous system effects when they reach the brain. This study assessed the concentrations and the time course of passage of vecuronium, atracurium, and its metabolite laudanosine in the cerebrospinal fluid (CSF) of patients undergoing intracranial aneurysm clipping.

METHODS

Twenty-five patients with subarachnoid hemorrhage were randomly allocated to receive an intravenous infusion of vecuronium (n=13) or atracurium (n=12). Arterial blood and lumbar CSF were sampled before and 1, 2, 3, 4 and 8 h after the start of the relaxant infusion. The samples were analyzed by liquid chromatography-electrospray ionization mass spectrometry (vecuronium) and high-pressure liquid chromatography (atracurium and laudanosine).

RESULTS

The data of 20 patients (10 in both groups) were analyzed. In 11 CSF samples from five patients atracurium was detected in concentrations from 10 to 50 ng/ml. Laudanosine was retrieved in all CSF samples at 1, 2, 3, 4 and 8 h; the highest CSF concentration of laudanosine occurred at 3 h [38 (18-63) ng/ml: median (range)]. Vecuronium was not found in any CSF sample.

CONCLUSION

Significant concentrations of atracurium and laudanosine but not of vecuronium were detected in the CSF of patients during and immediately after intracranial aneurysm surgery.

Closed humeral shaft fractures treated by elastic intramedullary retrograde nail

25 humeral shaft fractures operated on at our institute with the intramedullary elastic Marchetti-Vicenzi nail were reviewed. Three were pathologic fractures. Patients mean age was 48 ranging from 13 to 95 years. The patients were followed until consolidation and shoulder and elbow function were evaluated with respectively the Constant and the Mayo Clinic score. All the fractures eventually healed with good clinical results. There were no major complications during nail insertion. The M-V nail has been shown to be a practical and reliable device, characterised by both an easy technique and a stable fixation, with a low complication rate and low X-rays exposure times. The choice of an elastic unreamed intramedullary nail, with a retrograde insertion, that allows a solid for proximal fixation by means of a bundle of divergent pins, has proven to be useful and safe for shoulder function.

"Weak toxin" from Naja kaouthia is a nontoxic antagonist of alpha 7 and muscle-type nicotinic acetylcholine receptors

A novel "weak toxin" (WTX) from Naja kaouthia snake venom competes with [(125)I]alpha-bungarotoxin for binding to the membrane-bound Torpedo californica acetylcholine receptor (AChR), with an IC(50) of approximately 2.2 microm. In this respect, it is approximately 300 times less potent than neurotoxin II from Naja oxiana and alpha-cobratoxin from N. kaouthia, representing short-type and long-type alpha-neurotoxins, respectively. WTX and alpha-cobratoxin displaced [(125)I]alpha-bungarotoxin from the Escherichia coli-expressed fusion protein containing the rat alpha7 AChR N-terminal domain 1-208 preceded by glutathione S-transferase with IC(50) values of 4.3 and 9.1 microm, respectively, whereas for neurotoxin II the IC(50) value was >100 microm. Micromolar concentrations of WTX inhibited acetylcholine-activated currents in Xenopus oocyte-expressed rat muscle AChR and human and rat alpha7 AChRs, inhibiting the latter most efficiently (IC(50) of approximately 8.3 microm). Thus, a virtually nontoxic "three-fingered" protein WTX, although differing from alpha-neurotoxins by an additional disulfide in the N-terminal loop, can be classified as a weak alpha-neurotoxin. It differs from the short chain alpha-neurotoxins, which potently block the muscle-type but not the alpha7 AChRs, and is closer to the long alpha-neurotoxins, which have comparable potency against the above-mentioned AChR types.

Blockade and activation of the human neuronal nicotinic acetylcholine receptors by atracurium and laudanosine

BACKGROUND

Curaremimetic nondepolarizing muscle relaxants are widely used in clinical practice to prevent muscle contraction either during surgery or during intensive care. Although primarily acting at the neuromuscular junction, these compounds can cause adverse effects, including modification of cardiac rhythm, arterial blood pressure, and in the worst cases, triggering of seizures. In this study, we assessed the interaction of atracurium and its metabolite, laudanosine, with neuronal nicotinic receptors.

METHODS

The human neuronal nicotinic receptors alpha4beta2, alpha3beta4, alpha3alpha5beta4, and alpha7 are heterologously expressed in Xenopus laevis oocytes, and the effect of atracurium and its degradation product, laudanosine, were studied on these receptors.

RESULTS

Atracurium and laudanosine inhibited in the micromolar range the major brain alpha4beta2 receptor and the ganglionic alpha3beta4 or alpha3beta4alpha5 and the homomeric alpha7 receptors. For all four receptors, inhibition was rapid and readily reversible within less than 1 min. Atracurium blockade was competitive at alpha4beta2 and alpha7 receptors but displayed a noncompetitive blockade at the alpha3beta4 receptors. Inhibition at this receptor subtype was not modified by alpha5. Laudanosine was found to have a dual mode of action; first, it competes with acetylcholine and, second, it blocks the ionic pore by steric hindrance. At low concentrations, these two drugs are able to activate both the alpha4beta2 and the alpha3beta4 receptors.

CONCLUSION

Adverse effects observed during atracurium administration may be attributed, at least partly, to an interaction with neuronal nicotinic receptors.

A new look at the neuronal nicotinic acetylcholine receptor pharmacophore

Interest in the field of nicotinic receptors has been recently stimulated both by the discovery of the potential therapeutic effects of new agonists, and by the discovery of an association between nicotinic receptor mutations and human neurological diseases. Expression of human receptors in an exogenous system allows their study in isolation. Receptors reconstituted by pairwise injection of either alpha4 or alpha3 with beta2 or beta4 subunits displayed important differences between the resulting receptor subtypes. These results were further compared with those obtained with alpha3:alpha4 fusion proteins. The modifications of either the ligand-binding site in the N-terminal domain or in the ionic pore domain were found to affect the pharmacological properties of the receptors. Finally, the analysis of non-natural derivatives of epibatidine demonstrates how an agonist can be modified to be selective at one receptor subtype or to become an antagonist. These data are well explained on the basis of a three-state allosteric model.