Practical approaches to low density lipoprotein oxidation: whys, wherefores and pitfalls

The purpose of this review is to bring together the different approaches for studying the oxidation of low density lipoproteins and try to identify some critical factors which will permit greater comparability between laboratories. These issues are discussed both in terms of the variety of exogenous mediators of oxidation applied (transition metal ions, haem proteins, azo initiators, peroxynitrite, cells etc.) and their raisons d'être, as well as the methodologies (formation of conjugated dienes, hydroperoxides, decomposition products of lipid peroxidation, altered surface charge, macrophage uptake) applicable to the different stages of the oxidation and the factors underlying their accurate execution and interpretation.

The interaction between ruptured erythrocytes and low-density lipoproteins

Low-density lipoproteins (LDL) are oxidatively modified on interaction with haem proteins. The interaction of ruptured erythrocytes with LDL induces oxidative damage as detected by alterations in electrophoretic mobility and the peroxidation of the polyunsaturated fatty acyl chains. Difference spectroscopy reveals that the amplification of the oxidative process by the haem protein is related to the transition of the oxidation state of the haemoglobin in the erythrocyte lysate from the oxy [X-FeII-O2] to the ferryl [X-FeIV = O] form. The incorporation of the lipid-soluble antioxidant, butylated hydroxy toluene, at specific time points during the LDL-erythrocyte interaction prolongs the lag phase to oxidation and eliminates the oxy-to-ferryl conversion of the haemoglobin. The timescale of this haem conversion is related to the antioxidant status of the LDL.

MRI in Lhermitte-Duclos disease

Lhermitte-Duclos disease (LDD) is a disorder sometimes referred to as a dysplastic gangliocytoma of the cerebellum. This is a focally indolent growth of the cerebellar cortex in which the folia enlarge due to a profusion of dysplastic cortical neurons and a thickening of the molecular layer. Loss of Purkinje cells and thinning of medullary white matter results. The enlarged folia lose their secondary foldings and asymmetrically expand the cerebellar hemisphere. These morphologic features produce a characteristic pattern on some CTs and all MRIs, affording an opportunity for a preoperative diagnosis. MRI of a pathologic specimen suggested that the abnormal T1 and T2 signals corresponded to the atrophic folial white matter, thickened granule cell layer, and outer molecular layer. Because of inherent Hounsfield artifact in posterior fossa with CT, MRI is the imaging modality of choice, with better visualized striated pattern. The uniqueness of these imaging features obviates the need for an obligatory biopsy for asymptomatic patients and either permits more definitive planning for surgical decompression or, in restricted lesions, guides more assuredly complete excision of the cerebellar mass.

siRNA silencing of keratinocyte-specific GFP expression in a transgenic mouse skin model

Small interfering RNAs (siRNAs) can be designed to specifically and potently target and silence a mutant allele, with little or no effect on the corresponding wild-type allele expression, presenting an opportunity for therapeutic intervention. Although several siRNAs have entered clinical trials, the development of siRNA therapeutics as a new drug class will require the development of improved delivery technologies. In this study, a reporter mouse model (transgenic click beetle luciferase/humanized monster green fluorescent protein) was developed to enable the study of siRNA delivery to skin; in this transgenic mouse, green fluorescent protein reporter gene expression is confined to the epidermis. Intradermal injection of siRNAs targeting the reporter gene resulted in marked reduction of green fluorescent protein expression in the localized treatment areas as measured by histology, real-time quantitative polymerase chain reaction and intravital imaging using a dual-axes confocal fluorescence microscope. These results indicate that this transgenic mouse skin model, coupled with in vivo imaging, will be useful for development of efficient and 'patient-friendly' siRNA delivery techniques and should facilitate the translation of siRNA-based therapeutics to the clinic for treatment of skin disorders.

A complex containing CstF-64 and the SL2 snRNP connects mRNA 3' end formation and trans-splicing in C. elegans operons

Polycistronic pre-mRNAs from Caenorhabditis elegans are processed by 3' end formation of the upstream mRNA and SL2-specific trans-splicing of the downstream mRNA. These processes usually occur within an approximately 100-nucleotide region and are mechanistically coupled. In this paper, we report a complex in C. elegans extracts containing the 3' end formation protein CstF-64 and the SL2 snRNP. This complex, immunoprecipitated with alphaCstF-64 antibody, contains SL2 RNA, but not SL1 RNA or other U snRNAs. Using mutational analysis we have been able to uncouple SL2 snRNP function and identity. SL2 RNA with a mutation in stem/loop III is functional in vivo as a trans-splice donor, but fails to splice to SL2-accepting trans-splice sites, suggesting that it has lost its identity as an SL2 snRNP. Importantly, stem/loop III mutations prevent association of SL2 RNA with CstF-64. In contrast, a mutation in stem II that inactivates the SL2 snRNP still permits complex formation with CstF-64. Therefore, SL2 RNA stem/loop III is required for both SL2 identity and formation of a complex containing CstF-64, but not for trans-splicing. These results provide a molecular framework for the coupling of 3' end formation and trans-splicing in the processing of polycistronic pre-mRNAs from C. elegans operons.

Cloning of zebrafish neurofilament cDNAs for plasticin and gefiltin: increased mRNA expression in ganglion cells after optic nerve injury

During retinal growth and optic axon regeneration, the differential expression of the neuronal intermediate filament proteins, plasticin and gefiltin, in the goldfish visual pathway suggests that these proteins support programmed axonal growth. To investigate plasticin and gefiltin during axonogenesis, we turned to the zebrafish, a system that is more amenable to mutational analysis. As a first step, we demonstrated that the intermediate filament compositions of goldfish and zebrafish are similar. In addition, the cDNAs for zebrafish plasticin and gefiltin were cloned and characterized. Using in situ hybridization in retina, we show increased mRNA levels for these proteins following optic nerve crush. Zebrafish plasticin and gefiltin peak and return to baseline levels of expression more rapidly than in goldfish. Furthermore, in the unoperated eye of experimental fish, there was a moderate increase in the levels of plasticin and gefiltin mRNA, suggesting that soluble factors influence the expression of these proteins. The successive expression of plasticin and gefiltin suggests that these neuronal intermediate filament proteins are integral components of axonogenesis. The cloning and characterization of cDNAs for plasticin and gefiltin permit mutational analyses of these proteins during zebrafish axonogenesis.

Oxidisability of low density lipoproteins in patients with carotid or femoral artery atherosclerosis

Oxidation of low density lipoprotein (LDL) is implicated in the pathogenesis of atherosclerosis. In this study the susceptibility to oxidation of LDL (from patients with atherosclerosis) is related to the progression of the disease. LDL were isolated from 37 patients with demonstrable atherosclerotic plaques. The susceptibility of LDL to oxidation (induced by an exogenous oxidative stress) was assessed by measuring the breakdown products of lipid peroxidation, the increased formation of conjugated dienes, and changes in surface charge of the apolipoprotein B (apo B). Progression of the atherosclerotic plaque was assessed by measuring the maximum velocity of blood through the narrowest portion of the vessel at inclusion and after one year. Twenty-nine of the 37 samples taken were found to have LDL that were partially oxidised, whereas 8 samples showed LDL whose state of oxidation was within the normal range. Progression of the atherosclerotic plaque occurred in 19 (66%) of the 29 patients whose lipoproteins were partially oxidised compared with only 2 (25%) of the 8 patients with normal lipoproteins (P = 0.055, Fisher's exact test). These data support an association between the progression of atherosclerotic plaques in carotid and femoral vessels and the susceptibility to oxidation of LDL.

Gefiltin in zebrafish embryos: sequential gene expression of two neurofilament proteins in retinal ganglion cells

Neurogenesis is correlated with the progressive synthesis of diverse neuronal intermediate filaments (IF) proteins. This apparent developmental regulation of IF protein gene expression suggests that specific neurofilament proteins impart unique structural attributes that support the staged growth of the neuron. In the teleost visual pathway, the sequential expression of two IF genes, plasticin and gefiltin, is linked to the age of retinal ganglion cells (RGCs) and to the regeneration of optic axons after nerve injury. Given this pattern of plasticin and gefiltin expression, we hypothesized that the two proteins would be sequentially expressed in zebrafish retina during development. We analyzed the pattern of gefiltin expression during zebrafish development and compared it to our previous determination of plasticin expression (Canger et al. 1998). Gefiltin is expressed after plasticin, during the later stages of retinal development when axons grow past the optic chiasm and innervate their targets. Thus, during RGC development, expression of plasticin and gefiltin resembles that with optic nerve regeneration. Outside of the visual pathway, gefiltin is predominantly expressed in the central nervous system whereas plasticin is primarily expressed in the peripheral nervous system. These results suggest that the expression of these genes is regulated in a neuron-specific manner. In addition, since plasticin and gefiltin are co-expressed during RGC development, these findings suggest a more complex mechanism of transcriptional regulation which orchestrates the sequential expression of these genes.

Histologic evaluation of purified bovine tendon collagen sponge in tooth extraction sites in dogs

This study presents a histologic evaluation of the healing process of dental extraction sites in dogs with and without the use of collagen sponge as an extraction site dressing. The healing process was evaluated at 3 days, 1 week, and 6 months after tooth extraction and appears comparable in both collagen-filled and nonfilled extraction sites.

Prosthetic replacement of large defects of the cervical trachea in dogs

Surgical resection and replacement of a segment of the cervical trachea was performed in 8 mongrel dogs. The replacement was with a porous prosthesis made of Dacron cloth mesh stiffened with a heat-curing polyetherurethane. Ten tracheal rings were resected in each animal to create a complete circumferential defect of the trachea measuring 7 or 8 cm in length depending on the size of the dog. Animals were sacrificed periodically from 3 to 27 months post-reconstruction. The luminal surfaces of the reconstructed tracheae showed respiratory epithelium.

Restricted expression of the neuronal intermediate filament protein plasticin during zebrafish development

In the adult goldfish visual pathway, expression of the neuronal intermediate filament (nIF) protein plasticin is restricted to differentiating retinal ganglion cells (RGCs) at the margin of the retina. Following optic nerve injury, plasticin expression is elevated transiently in all RGCs coincident with the early stages of axon regeneration. These results suggest that plasticin may be expressed throughout the nervous system during the early stages of axonogenesis. To test this hypothesis, we analyzed plasticin expression during zebrafish (Danio rerio) neuronal development. By using immunocytochemistry and in situ hybridization, we found that plasticin is expressed in restricted subsets of early zebrafish neurons. Expression coincides with axon outgrowth in projection neurons that pioneer distinct axon tracts in the embryo. Plasticin is expressed first in trigeminal, Rohon-Beard, and posterior lateral line ganglia neurons, which are among the earliest neurons to initiate axonogenesis in zebrafish. Plasticin is expressed also in reticulospinal neurons and in caudal primary motoneurons. Together, these neurons establish the first behavioral responses in the embryo. Plasticin expression also coincides with initial RGC axonogenesis and progressively decreases after RGC axons reach the tectum. At later developmental stages, plasticin is expressed in a subset of the cranial nerves. The majority of plasticin-positive neurons are within or project axons to the peripheral nervous system. Our results suggest that plasticin subserves the changing requirements for plasticity and stability during axonal outgrowth in neurons that project long axons.

Neurocranial reconstruction using an elastomer-coated cloth mesh and bone grafting

The purpose of this report is to present out 5-year experience in reconstructing large bony defects in the cranial vault of 16 patients. The method employs an alloplastic implant device made of elastomer-coated cloth mesh, used in conjunction with bone grafting [D. L. Leake and M. Habal, J. Biomed. Mater. Res., 10, 555 (1976)]. The cranial defects ranged in size from 6 X 6 cm to 15 X 17 cm. The defects were in the frontal, temporoparietal, and occipital regions. Particularly challenging was the frontal-orbital region involving the superciliary ridges. The alloplastic implant provides controlled contour of the bone graft material while providing strength and stability during healing. The implant has adequate but not complete ridigity, allowing adaptability inthe operating room. The elastomer used is a polyetherurethane. Any biocompatible cloth mesh can be used, but Dacron [poly(ethylene terephthalate)] was chosen because of its extensive implant history. Contrasted with reconstruction using only bone, where as many as half of the cases had uneveness and were found to be anesthetically unsatisfactory, the technique described here has resulted in aesthetically excellent results and an intact neurocranium in the 16 patients studied thus far.

Carbon-coated subperiosteal dental implants for fixed and movable prostheses

Subperiosteal dental implants are not intended to replace conventional dentistry but provide an alternative method of treatment for the patient who cannot otherwise tolerate a dental prosthesis. Success can be achieved in the maxillae and in the mandible without the risk of serious complications. There are good prospects for a long-term favorable prognosis when appropriate surgical and prosthodontic criteria are observed.

Prevalence of SARS-CoV-2 antibodies in pediatric healthcare workers

Objectives

To determine SARS-CoV-2-antibody prevalence in pediatric healthcare workers (pHCWs).

Design

Baseline prevalence of anti-SARS-CoV-2-IgG was assessed in a prospective cohort study from a large pediatric healthcare facility. Prior SARS-CoV-2 testing history, potential risk factors and anxiety level about COVID-19 were determined. Prevalence difference between emergency department (ED)-based and non-ED-pHCWs was modeled controlling for those covariates. Chi-square test-for-trend was used to examine prevalence by month of enrollment.

Results

Most of 642 pHCWs enrolled were 31-40years, female and had no comorbidities. Half had children in their home, 49% had traveled, 42% reported an illness since January, 31% had a known COVID-19 exposure, and 8% had SARS-CoV-2 PCR testing. High COVID-19 pandemic anxiety was reported by 71%. Anti-SARS-CoV-2-IgG prevalence was 4.1%; 8.4% among ED versus 2.0% among non-ED pHCWs (p < 0.001). ED-work location and known COVID-19 exposure were independent risk factors. 31% of antibody-positive pHCWs reported no symptoms. Prevalence significantly (p < 0.001) increased from 3.0% in April–June to 12.7% in July–August.

Conclusions

Anti-SARS-CoV-2-IgG prevalence was low in pHCWs but increased rapidly over time. Both working in the ED and exposure to a COVID-19-positive contact were associated with antibody-seropositivity. Ongoing universal PPE utilization is essential. These data may guide vaccination policies to protect front-line workers.

Studying biological science does not lead to adoption of a healthy lifestyle

AIMS

The lifestyle and physical activity (PA) habits of young people play a key role in the prevention of cardiovascular and metabolic diseases at older ages. The current generation of biological science students at university holds promise for better future medicine and medical technology. However, their physical fitness and lifestyle are often ignored.

METHODS

Lifestyle, PAs and common risk factors for cardiovascular disease before, and at, university were collected from 408 students using self-completed, anonymous surveys between the academic years of 2017 and 2019 from the School of Biological Sciences, University of Reading. Statistical analysis was performed using SAS® 9.4 software.

RESULTS

Among the 408 participants, 134 were male and 274 were female with a mean (SD) age of 19.6 (2.24). Approximately 19% of participants consumed alcohol beyond the safe limit of <14 units/week (112 g/week). Among them, 65% were males. Before university, 47% of students failed to meet the UK National Physical Activity Guidelines (NPAG) which increased to 56% during university with males exhibiting a steeper incline. Compared to their lifestyles before university, more students had insufficient sleep and displayed greater sedentariness during university. Moreover, 16% of students declared no engagement in PA which was greater than the value of 12% before university. Fitness perceptions worsened by 11% during university particularly for females. Statistical analysis revealed that gender, BMI and fitness perceptions were significantly correlated with PA levels. The most prevalent explanation for inadequacy in meeting NPAG was insufficient time.

CONCLUSIONS

Compared to their pre-university lifestyles, biological science students at university are more likely to adopt unhealthier behaviours with less time for exercise and prolonged sedentary behaviours, which increases the risk for cardiovascular diseases. It is important to raise awareness of their fitness perceptions and to encourage health-promoting programmes at university.

Mandibular reconstruction and craniofacial fairing

A method of restoring bony contour defects in the craniofacial regions employing a combination graft of autogenous bone and an alloplastic mesh is presented. Osteoinduction occurs within the confines of the alloplastic mesh from the cancellous bone and the resultant new bone conforms to the outline imposed by the alloplastic device. The advantages of this method include those of alloplastic materials combined with those of bone grafting. There is immediate restoration of an aesthetic contour with adequate strength and sound fixation.

Preliminary histologic evaluation of a biocompatible mesh for tracheal reconstruction

The purpose of this study was to evaluate a porous Dacron - urethane mesh tracheal prosthesis in large dogs with surgically created discontinuous defects of the cervical trachea. Some protheses were carbon coated in an attempt to improve biocompatibility. Histology was performed on 2 dogs. The mucosa regenerated entirely covering the prosthesis. Respiratory epithelium was formed over a large central portion of the tracheas.

Sickle Cell Disease Treatment with Arginine Therapy (STArT): study protocol for a phase 3 randomized controlled trial

BACKGROUND

Despite substantial illness burden and healthcare utilization conferred by pain from vaso-occlusive episodes (VOE) in children with sickle cell disease (SCD), disease-modifying therapies to effectively treat SCD-VOE are lacking. The aim of the Sickle Cell Disease Treatment with Arginine Therapy (STArT) Trial is to provide definitive evidence regarding the efficacy of intravenous arginine as a treatment for acute SCD-VOE among children, adolescents, and young adults.

METHODS

STArT is a double-blind, placebo-controlled, randomized, phase 3, multicenter trial of intravenous arginine therapy in 360 children, adolescents, and young adults who present with SCD-VOE. The STArT Trial is being conducted at 10 sites in the USA through the Pediatric Emergency Care Applied Research Network (PECARN). Enrollment began in 2021 and will continue for 5 years. Within 12 h of receiving their first dose of intravenous opioids, enrolled participants are randomized 1:1 to receive either (1) a one-time loading dose of L-arginine (200 mg/kg with a maximum of 20 g) administered intravenously followed by a standard dose of 100 mg/kg (maximum 10 g) three times a day or (2) a one-time placebo loading dose of normal saline followed by normal saline three times per day at equivalent volumes and duration as the study drug. Participants, research staff, and investigators are blinded to the participant's randomization. All clinical care is provided in accordance with the institution-specific standard of care for SCD-VOE based on the 2014 National Heart, Lung, and Blood Institute guidelines. The primary outcome is time to SCD-VOE pain crisis resolution, defined as the time (in hours) from study drug delivery to the last dose of parenteral opioid delivery. Secondary outcomes include total parental opioid use and patient-reported outcomes. In addition, the trial will characterize alterations in the arginine metabolome and mitochondrial function in children with SCD-VOE.

DISCUSSION

Building on the foundation of established relationships between emergency medicine providers and hematologists in a multicenter research network to ensure adequate participant accrual, the STArT Trial will provide definitive information about the efficacy of intravenous arginine for the treatment of SCD-VOE for children.

TRIAL REGISTRATION

The STArT Trial was registered in ClinicalTrials.gov on April 9, 2021, and enrollment began on June 21, 2021 (NCT04839354).

Vapor-deposited carbon-coated tooth root implants: preliminary evaluation of a stylized tooth implant system in dogs

The results of this preliminary evaluation of a tooth implant model combining a stylized tooth root design and a thin, highly biocompatible microporous carbon coating, although tentative, add support to the feasibility of developing a statisfactory system for the immediate replacement of selected teeth in healthy bone.

A new arch bar for oral surgery

A new universal arch bar for intermaxillary fixation has been developed. This arch bar was fabricated as a wave-shaped, thin metal plate with soldered buttons on the bucco-labial aspect. It is light and flexible, yet strong enough to provide excellent fixation in the treatment of fractures of the maxilla and/or mandible. It is a universal bar: the superior and inferior borders are identical. Clinical application has been broad including trauma and cases of orthognathic surgery.

Direction or inertia: the future for regulation of surgical implant devices

The time has arrived when certain standards are to be introduced to control the introduction of and appropriate use of surgical implant devices. Now is the time for the professional groups involved in standards and medical device legislation to become active and develop surgical implant device standards to be applicable for the future. A commission could be established to work with FDA in respect to the requirements for surgical implant devices. It is time for the clinical organizations involved in writing consensus standards to cooperate in the introduction of surgical implant device standards.