Pfeiffer type 2 syndrome: review with updates on its genetics and molecular biology

INTRODUCTION

Pfeiffer syndrome is a rare autosomal dominant inherited disorder associated with craniosynostosis, midfacial hypoplasia, and broad thumbs and toes. The syndrome has been divided into three clinical subtypes based on clinical findings.

METHODS

This review will specifically examine the most severe type, Pfeiffer syndrome type 2, focusing on its genetics and molecular biology.

CONCLUSION

This subtype of the syndrome is caused by de novo sporadic mutations, the majority of which occur in the fibroblast growth factor receptor type 1 and 2 (FGFR1/2) genes. There is not one specific mutation, however. This disorder is genetically heterogeneous and may have varying phenotypic expressions that in various cases have overlapped with other similar craniosynostoses. A specific missense mutation of FGFR2 causing both Pfeiffer and Crouzon syndromes has been identified, with findings suggesting that gene expression may be affected by polymorphism within the same gene. Compared to other craniosynostosis-related disorders, Pfeiffer syndrome is the most extreme phenotype, as the underlying mutations cause wider effects on the secondary and tertiary protein structures and exhibit harsher clinical findings.

The Great Auricular Nerve: Anatomical Study with Application to Nerve Grafting Procedures

BACKGROUND

When it comes to autogenous nerve grafting, the sural and great auricular nerve (GAN) are the 2 nerves predominately used for trigeminal and facial nerve repair. Arising from the second and third cervical ventral rami, the GAN emerges from the posterior border of the sternocleidomastoid coursing superiorly and anteriorly toward the ear.

METHODS

Eleven sides from 5 Caucasian and 1 Asian cadaveric heads (all fresh-frozen) were used. One man and 5 women were used with an age at death ranging from 57 to 91 years, with a mean of 80.3 years. Measurements were made from the inferior border of the ear to the GAN, the GAN to the external jugular vein, and the inferior border of the mastoid process to the GAN; the proximal, medial, and distal diameters of the GAN and the length of the GAN that was obtained from this exposure were also measured.

RESULTS

The mean distance from the inferior border of the mastoid process to the GAN, inferior border of the ear to the GAN, and GAN to the external jugular vein was 27.71, 31.03, and 13.28 mm, respectively. The mean length of the GAN was 74.86 mm. The mean diameter of its distal, middle, and proximal portions was 1.51, 1.38, and 1.58 mm, respectively.

CONCLUSIONS

The GAN is an excellent option for use in nerve grafting for repair of, for example, facial dysfunction. In this study, we review our measurements, techniques for identification, and dissecting techniques for the GAN. The proximity to the operative area and minimal complications associated with GAN grafting might contribute to improved patient satisfaction and better outcomes regarding functional restoration.

Gerber's Ligament-A Forgotten Structure of the Craniocervical Junction

BACKGROUND

Ligaments of the craniocervical junction play a critical role in stabilizing this region. Gerber's ligament has more or less been forgotten and, to our knowledge, never studied.

METHODS

Dissection of the craniocervical junction was performed in 15 fresh frozen cadavers. In the prone position, the posterior elements of the upper cervical vertebrae and occiput were removed. After removing the contents of the spinal canal and posterior cranial fossa, the dura mater and tectorial membrane were reflected. The superior band of the cruciform ligament was reflected. When Gerber's ligament was identified, its attachments and morphometry were recorded. Lastly, Gerber's ligament was observed while range of motion of the craniocervical junction was performed.

RESULTS

Gerber's ligament was identified in 7 specimens (46.7%). This structure arose anteriorly from the junction of the superior band and transverse part of the cruciform ligament. Gerber's ligament was always found to be just deep to the superior band of the cruciform ligament but traveled more anteriorly to attach onto the posterior aspect of the dens approaching, but not attaching onto, its apex. Mean length was 11 mm, and mean width was 7 mm. Thickness of the ligament was 0.5-1.1 mm. The ligament was found to become taut with minimal rotation of the atlantoaxial joint and extension of the craniocervical junction.

CONCLUSIONS

A good understanding of all ligaments of the craniocervical junction is important to surgeons and physicians treating patients with injury to the upper cervical spine.

Bilateral sternocleidomastoid variant with six distinct insertions along the superior nuchal line

Anatomical variations of the sternocleidomastoid muscle (SCM) have been observed to occupy multiple origins and insertion points and have supernumerary heads, sometimes varying in thickness. During routine dissection, a SCM was observed to have six distinct insertions that interface with the course of the superior nuchal line, ending at the midline, bilaterally. This variation was also seen to receive innervation from the accessory nerve as well as the great auricular nerve. To our knowledge, this variant of supernumerary insertions and nerve innervations has not yet been reported. These variants may pose as problematic during surgical approaches to the upper neck and occiput, and should thus be appreciated by the clinician. Herein we discuss the case report, possible embryological origins, and the clinical significance of the observed variant SCM.

Human embryonic stem cells: Distinct molecular personalities and applications in regenerative medicine

The field of stem cell biology is exciting because it provides researchers and clinicians with seemingly unlimited applications for treating many human diseases. Stem cells are a renewable source of pluripotent cells that can differentiate into nearly all human cell types. In this article we focus particularly on human embryonic stem (hES) cells, derived from the inner cell mass of the blastocyst and cultured for expansion while remaining undifferentiated, to explore their unique molecular personalities and clinical applications. The aim of this literature review is to reflect the interest in hES cells and to provide a resource for researchers and clinicians interested in the molecular characteristics of such cells. Clin. Anat. 32:354–360, 2019. © 2018 The Authors. Clinical Anatomy published by Wiley Periodicals, Inc. on behalf of American Association of Clinical Anatomists.

A Median Artery of the Corpus Callosum

The anterior communicating artery is one of the main components of the vascular network that delivers blood to the brain. Therefore, a good understanding of the normal anatomy and its variations is important to neurologists, neurosurgeons, and other health care providers dealing with the central nervous system. Here, we present a case of a median artery of the corpus callosum found in a cadaver, with consideration of cerebral hemodynamics implications.

A Variant of the Sciatic Nerve and its Clinical Implications

Variants of gluteal neural anatomy are important to consider, especially during surgical approaches to the hip. During the routine dissection of the gluteal region, a variant of the sciatic nerve was found where the nerve left the pelvis fully split into its tibial and common fibular components. Intrapelvically and extrapelvically, there was no splitting of the two components by the piriformis muscle. Distally, the two parts of the nerve were draped over the medial and lateral edges of the ischial tuberosity. To avoid iatrogenic injury to the sciatic nerve during invasive or surgical approaches to this region, all possible anatomical variations, such as the one presented herein, should be appreciated by the clinician.

[NEW SURGICAL APPROACH IN PRIMARY OPEN-ANGLE GLAUCOMA: XEN GEL STENT A MINIMALLY INVASIVE TECHNIQUE]

Primary open-angle glaucoma is a progressive ocular disease affecting adults and associated with visual field defect. The aim of its treatment is to lower the ocular pressure by means of ocular drops, laser or surgery. To date, traditional surgical techniques still remain quite invasive, but recent research efforts have been made with a view to develop minimally invasive techniques. The Xen Gel Stent is one of them. It allows a safe and efficient lowering of ocular pressure by creating a sub-conjunctival flow, following an ab interno procedure that highly preserves the architecture of the treated eye.

Systems biology of cellular rhythms

Rhythms abound in biological systems, particularly at the cellular level where they originate from the feedback loops present in regulatory networks. Cellular rhythms can be investigated both by experimental and modeling approaches, and thus represent a prototypic field of research for systems biology. They have also become a major topic in synthetic biology. We review advances in the study of cellular rhythms of biochemical rather than electrical origin by considering a variety of oscillatory processes such as Ca++ oscillations, circadian rhythms, the segmentation clock, oscillations in p53 and NF-κB, synthetic oscillators, and the oscillatory dynamics of cyclin-dependent kinases driving the cell cycle. Finally we discuss the coupling between cellular rhythms and their robustness with respect to molecular noise.

CCR9+ T cells contribute to the resolution of the inflammatory response in a mouse model of intestinal amoebiasis

Analysis of the mechanisms underlying the inflammatory response in amoebiasis is important to understand the immunopathology of the disease. Mucosal associated effector and regulatory T cells may play a role in regulating the inflammatory immune response associated to Entamoeba histolytica infection in the colon. A subpopulation of regulatory T cells has recently been identified and is characterized by the expression of the chemokine receptor CCR9. In this report, we used CCR9 deficient (CCR9(-/-)) mice to investigate the role of the CCR9(+) T cells in a murine model of E. histolytica intestinal infection. Intracecal infection of CCR9(+/+), CCR9(+/-) and CCR9(-/-) mice with E. histolytica trophozoites, revealed striking differences in the development and nature of the intestinal inflammatory response observed between these strains. While CCR9(+/+) and CCR9(+/-) mice were resistant to the infection and resolved the pathogen-induced inflammatory response, CCR9(-/-) mice developed a chronic inflammatory response, which was associated with over-expression of the cytokines IFN-γ, TNF-α, IL-4, IL-6 and IL-17, while IL-10 was not present. In addition, increased levels of CCL11, CCL20 and CCL28 chemokines were detected by qRT-PCR in CCR9(-/-) mice. E. histolytica trophozoites were identified in the lumen of the cecum of CCR9(-/-) mice at seven days post infection (pi), whereas in CCR9(+/+) mice trophozoites disappeared by day 1 pi. Interestingly, the inflammation observed in CCR9(-/-) mice, was associated with a delayed recruitment of CD4(+)CD25(+)FoxP3(+) T cells to the cecal epithelium and lamina propria, suggesting that this population may play a role in the early regulation of the inflammatory response against E. histolytica, likely through IL-10 production. In support of these data, CCR9(+) T cells were also identified in colon tissue sections obtained from patients with amoebic colitis. Our data suggest that a population of CCR9(+)CD4(+)CD25(+)FoxP3(+) T cells may participate in the control and resolution of the inflammatory immune response to E. histolytica infection.

Hyperoxia does not accelerate quadriceps muscle deoxygenation kinetics at the onset of heavy exercise cycle

AIM

The aim of this study was to determine whether an increase in O2 availability induces an alteration of the balance between O2 consumption ((V)O2) and O2 delivery ((Q)O2) at the muscle level. For that, we examined the effect of moderate hyperoxia on muscle deoxygenation kinetics at the onset of heavy-intensity cycling exercise.

METHODS

Eight young male adults performed step transitions from 35 W to heavy-intensity exercise corresponding to a power output half-way between the first ventilatory threshold and (V)O2max in normoxia and in hyperoxia (FIO2=0.30). Muscle deoxygenation (HHb) and total hemoglobin (Hbtot) were monitored continuously by near-infrared spectroscopy. HHb data were fit with a mono-exponential model from the onset of exercise up to 90 seconds.

RESULTS

Hyperoxia neither altered the delay before the increase in HHb (normoxia: 10.7±1.8 s vs. hyperoxia: 9.5±1.9 s; NS) nor the HHb mean response time (normoxia: 20.6±2.8 s vs. hyperoxia: 19.6±2.3 s; NS). Likewise, Hbtot was not different between normoxia and hyperoxia.

CONCLUSION

These results indicate that moderate hyperoxia has no effect on muscle deoxygenation kinetics at the onset of heavy exercise. It suggests that muscle (V)O2 increases at the same rate than O2 delivery when O2 availability is enhanced.

Investigation of the role of sigma1-receptors in inositol 1,4,5-trisphosphate dependent calcium signaling in hepatocytes

In hepatocytes, as in other cell types, Ca(2+) signaling is subject to complex regulations, which result largely from the intrinsic characteristics of the different inositol 1,4,5-trisphosphate receptor (InsP(3)R) isoforms and from their interactions with other proteins. Although sigma1 receptors (Sig-1Rs) are widely expressed in the liver, their involvement in hepatic Ca(2+) signaling remains unknown. We here report that in this cell type Sig-1R interact with type 1 isoforms of the InsP(3) receptors (InsP(3)R-1). These results obtained by immunoprecipitation experiments are confirmed by the observation that Sig-1R proteins and InsP(3)R-1 colocalize in hepatocytes. However, Sig-1R ligands have no effect on InsP(3)-induced Ca(2+) release in hepatocytes. This can be explained by the rather low expression level expression of InsP(3)R-1. In contrast, we find that Sig-1R ligands can inhibit agonist-induced Ca(2+) signaling via an inhibitory effect on InsP(3) synthesis. We show that this inhibition is due to the stimulation of PKC activity by Sig-1R, resulting in the well-known down-regulation of the signaling pathway responsible for the transduction of the extracellular stimulus into InsP(3) synthesis. The PKC sensitive to Sig-1R activity belongs to the family of conventional PKC, but the precise molecular mechanism of this regulation remains to be elucidated.

[VEGF inhibitors in ophthalmology]

The exsudative form of age-related macular degeneration (AMD) is characterized by the development of choroidal neovascularization (CNV) under the retina driven in part by the vascular endothelial growth factor. Several VEGF inhibitors have recently been produced for ocular administration. This review will focus on ranibizumab which is a specific antibody neutralizing all VEGF isoforms. The development, pharmacokinetics, clinical efficacy, current and future indications of ranibizumab are discussed.

[Vitreoretinal outpatient surgery: clinical and financial considerations]

INTRODUCTION

Vitreoretinal surgery has benefited from great advances opening the opportunity for outpatient management.

METHODS

We report on the 6-month experience of outpatient surgery for vitreoretinal diseases.

RESULTS

From November 2007 to April 2008, 270 patients benefited from a vitreoretinal surgery, with 173 retinal detachments, 63 epiretinal membranes, and 34 other procedures. Only 8.5% (n=23) of the patients had to stay at the hospital one or two nights. The main reasons were the distance from the hospital and surgery on a single-eye patient. The questionnaire given after the surgery showed that almost all the patients were satisfied with the outpatient setting. In contrast, the financial results showed a loss of income of around 400,000 euros due to the low level of payment of outpatient surgery in France by the national health insurance system.

DISCUSSION

Vitreoretinal surgery can be achieved in outpatient surgery with an improvement in the information given to the patients and the overall organization of the hospitalization. However, the current income provided with vitreoretinal outpatient surgery is highly disadvantageous in France, preventing this method from being generalized.

Complex intracellular calcium oscillations. A theoretical exploration of possible mechanisms

Intracellular Ca(2+) oscillations are commonly observed in a large number of cell types in response to stimulation by an extracellular agonist. In most cell types the mechanism of regular spiking is well understood and models based on Ca(2+)-induced Ca(2+) release (CICR) can account for many experimental observations. However, cells do not always exhibit simple Ca(2+) oscillations. In response to given agonists, some cells show more complex behaviour in the form of bursting, i.e. trains of Ca(2+) spikes separated by silent phases. Here we develop several theoretical models, based on physiologically plausible assumptions, that could account for complex intracellular Ca(2+) oscillations. The models are all based on one- or two-pool models based on CICR. We extend these models by (i) considering the inhibition of the Ca(2+)-release channel on a unique intracellular store at high cytosolic Ca(2+) concentrations, (ii) taking into account the Ca(2+)-activated degradation of inositol 1,4,5-trisphosphate (IP(3)), or (iii) considering explicity the evolution of the Ca(2+) concentration in two different pools, one sensitive and the other one insensitive to IP(3). Besides simple periodic oscillations, these three models can all account for more complex oscillatory behaviour in the form of bursting. Moreover, the model that takes the kinetics of IP(3) into account shows chaotic behaviour.

Anaerobic Running Capacity Determined from a 3-Parameter Systems Model: Relationship with other Anaerobic Indices and with Running Performance in the 800 m-Run

The purpose of this study was to compare anaerobic running capacity (ARC, i.e., the distance that can be run using only stored energy sources in the muscle) determined from a 3-parameter systems model with other anaerobic indices and with running performance in the 800 m. Seventeen trained male subjects (.VO(2max) = 66.54 +/- 7.29 ml . min (-1) . kg (-1)) performed an incremental test to exhaustion for the determination of .VO(2max) and peak treadmill velocity (PTV), five randomly ordered constant velocity tests at 95, 100, 105, 110, and 120 % of PTV to compute ARC and oxygen deficit (O(2)def, at 110 % of PTV), and a 800-m time trial to determine running performance (mean velocity over the distance, V (800 m)) and peak blood lactate concentration ([La (-)] (b, peak)). ARC (467 +/- 123 m) was positively correlated with O(2)def (56.35 +/- 18.47 ml . kg (-1); r = 0.57; p < 0.05), but not with [La (-)] (b, peak) (15.08 +/- 1.48 mmol . l (-1); r = - 0.16; p > 0.05). The O(2) equivalent of ARC (i.e., the product of ARC by the energy cost of running; 103.74 +/- 28.25 ml . kg (-1)), which is considered as an indirect estimation of O(2)def, was significantly higher than O(2)def (p < 0.01, effect size = 1.99). It was concluded that ARC is partially determined by anaerobic pathway, but that it probably does not provide an accurate measure of anaerobic capacity, if, however, O(2)def can be considered as a criterion measure for it.

V·O2 Kinetics during Supramaximal Exercise: Relationship with Oxygen Deficit and 800-m Running Performance

The aim of this study was to compare .VO2 kinetics of highly- versus recreationally-trained subjects during a constant velocity test of supramaximal intensity. Eighteen trained male subjects were recruited to one of two groups: highly trained (HT, n = 8, .VO(2max) = 70.1 +/- 6.5 ml . min (-1) . kg (-1)) and recreationally trained (RT, n = 10, .VO(2max) = 63.2 +/- 6.4 ml . min (-1) . kg (-1)). All subjects performed an incremental test to exhaustion for the determination of .VO(2max) and peak treadmill velocity (PTV), two constant velocity tests at 110 % of PTV to determine .VO2 kinetics and oxygen deficit (O(2)def), and a 800-m time trial to determine running performance (mean velocity over the distance, V (800 m)). We found significant differences between HT and RT for the on-transient of the .VO2 response (tau, 24.7 +/- 3.3 and 30.9 +/- 7.0 s, respectively), the amplitude of the .VO2 response (60.0 +/- 5.0 and 53.5 +/- 5.7 ml . min (-1) . kg (-1), respectively) and V (800 m) (6.27 +/- 2.1 and 5.45 +/- 0.38 m . s (-1), respectively). O(2)def (24.6 +/- 2.7 and 27.7 +/- 7.8 ml . kg (-1), respectively) and the gain of the .VO2 response (193 +/- 14 and 194 +/- 13 ml . kg (-1) . m (-1), respectively) were similar between groups. tau was associated with O(2)def (r = 0.90, p < 0.05), but not with V (800 m) (r = 0.30, p > 0.05). It was concluded that HT subjects exhibited faster on-kinetics and higher amplitude than their RT counterparts. The higher amplitude was not thought to reflect any difference in underlying physiological mechanisms. The faster tau, whose exact mechanisms remain to be elucidated, may have practical implications for coaches.