Evaluation of facial fat distribution using magnetic resonance imaging

Magnetic resonance imaging (MRI) provides noninvasive images of facial and neck fat for a variety of conditions. It accurately maps the soft tissues pre- and postoperatively, enabling surgeons to precisely and objectively assess results of soft tissue facial contouring and fat transplantation. The risks of MRI are few. It has the potential to provide aesthetic surgeons with a more scientific means of comparing various techniques of fat contouring.     

Associations between two common variants C677T and A1298C in the methylenetetrahydrofolate reductase gene and measures of folate metabolism and DNA stability (strand breaks, misincorporated uracil, and DNA methylation status) in human lymphocytes in vivo.

OBJECTIVE: Homozygosity for variants of the methylenetetrahydrofolate reductase (MTHFR) gene is associated with decreased risk for colorectal cancer. We have investigated the relationships between two variants of the MTHFR gene (C677T and A1298C) and blood folate, homocysteine, and genomic stability (strand breakage, misincorporated uracil, and global cytosine methylation in lymphocytes) in a study of 199 subjects. RESULTS: The frequencies of homozygosity for the C677T and A1298C variants of the MTHFR gene were 12.6% and 14.6%, respectively. Plasma homocysteine, folate, vitamin B12, 5-methyltetrahydrofolate, and RBC folate were determined in the C677T genotypes. Plasma folate was significantly lower (P < 0.001) in the homozygous variants (6.7 +/- 0.6 ng/mL) compared with wild-types (8.8 +/- 0.4 ng/mL) and heterozygotes (9.1 +/- 0.5 ng/mL). Homocysteine was significantly higher (P < 0.05) in homozygous variants (13.2 +/- 1.1 micromol/L) compared with homozygous subjects (10.9 +/- 0.4 micromol/L). Homozygous variants had significantly lower (P < 0.05) RBC folate (84.7 +/- 6.3 ng/mL) compared with wild-types (112.2 +/- 5.2 ng/mL) and heterozygous individuals (125.1 +/- 6.6 ng/mL). No significant difference in RBC folate was observed between wild-types and heterozygotes. The A1298C variant did not influence plasma homocysteine, folate, 5-methyltetrahydrofolate, vitamin B12, or RBC folate. Lymphocyte DNA stability biomarkers (strand breaks, misincorporated uracil, and global DNA methylation) were similar for all MTHFR C677T or A1298C variants. CONCLUSION: Data from this study do not support the hypothesis that polymorphisms in the MTHFR gene increase DNA stability by sequestering 5,10-methylenetetrahydrofolate for thymidine synthesis and reducing uracil misincorporation into DNA.     

Expression of a synapse-associated membrane protein, P84/SHPS-1, and its ligand, IAP/CD47, in mouse retina

P84 and integrin associated protein (IAP) are heterophilic binding partners that are expressed in the central nervous system in addition to a variety of other tissues. Both molecules are known to be involved in cell signaling in nonneural tissues. In the retina, both molecules are expressed prominently in plexiform layers, suggesting a possible association with synapses. Here, we examined the cellular expression and ultrastructural localization of the two molecules in the developing mouse retina. Both appeared to be expressed at one or both sides of synaptic sites, although the expression of IAP in the retina precedes that of P84. Examination of transgenic IAP-null retinae revealed a failure of P84 to become associated with synaptic sites, suggesting the interaction of P84 with IAP was necessary for P84's synaptic localization. These findings suggest that the signaling activities of P84 and IAP are localized to sites of synaptic contact in the retina. Thus this pair of synapse-associated molecules represents a bidirectional signaling system that could function to modify synaptic activity or possibly trophic interactions between central neurons.     

Dorsolateral prefrontal cortex and the implicit association of concepts and attributes

The Implicit Association Test (IAT) examines the differential association of two object categories (e.g. flower and insect) with attribute categories (e.g. pleasant and unpleasant). When items from congruent categories (e.g. flower + pleasant) share a response key, performance is faster and more accurate than when items from incongruent categories (e.g. insect + pleasant) share a key. Performing incongruent word classification engages inhibitory processes to overcome the prepotent tendency to map emotionally congruent items to the same response key. Using fMRI on subjects undergoing the IAT, we show that the left dorsolateral prefrontal cortex, and to a lesser extent the anterior cingulate cortex, mediate inhibitory processes where manipulation of word association is required.     

Distal femoral extension osteotomy and patellar tendon advancement or shortening in ambulatory children with cerebral palsy: A modified Delphi consensus study and literature review

Purpose:In children with cerebral palsy, flexion deformities of the knee can be treated with a distal femoral extension osteotomy combined with either patellar tendon advancement or patellar tendon shortening. The purpose of this study was to establish a consensus through expert orthopedic opinion, using a modified Delphi process to describe the surgical indications for distal femoral extension osteotomy and patellar tendon advancement/patellar tendon shortening. A literature review was also conducted to summarize the recent literature on distal femoral extension osteotomy and patellar tendon shortening/patellar tendon advancement.Method:A group of 16 pediatric orthopedic surgeons, with more than 10 years of experience in the surgical management of children with cerebral palsy, was established. The group used a 5-level Likert-type scale to record agreement or disagreement with statements regarding distal femoral extension osteotomy and patellar tendon advancement/patellar tendon shortening. Consensus for the surgical indications for distal femoral extension osteotomy and patellar tendon advancement/patellar tendon shortening was achieved through a modified Delphi process. The literature review, summarized studies of clinical outcomes of distal femoral extension osteotomy/patellar tendon shortening/patellar tendon advancement, published between 2008 and 2022.Results:There was a high level of agreement with consensus for 31 out of 44 (70%) statements on distal femoral extension osteotomy. Agreement was lower for patellar tendon advancement/patellar tendon shortening with consensus reached for 8 of 21 (38%) of statements. The literature review included 25 studies which revealed variation in operative technique for distal femoral extension osteotomy, patellar tendon advancement, and patellar tendon shortening. Distal femoral extension osteotomy and patellar tendon advancement/patellar tendon shortening were generally effective in correcting knee flexion deformities and extensor lag, but there was marked variation in outcomes and complication rates.Conclusion:The results from this study will provide guidelines for surgeons who care for children with cerebral palsy and point to unresolved questions for further research.Level of evidence:level V.     

Hyperimmunized Chickens Produce Neutralizing Antibodies against SARS-CoV-2

The novel severe acute respiratory syndrome (SARS) coronavirus, SARS-CoV-2, is responsible for the global COVID-19 pandemic. Effective interventions are urgently needed to mitigate the effects of COVID-19 and likely require multiple strategies. Egg-extracted antibody therapies are a low-cost and scalable strategy to protect at-risk individuals from SARS-CoV-2 infection. Commercial laying hens were hyperimmunized against the SARS-CoV-2 S1 protein using three different S1 recombinant proteins and three different doses. Sera and egg yolk were collected at three and six weeks after the second immunization for enzyme-linked immunosorbent assay and plaque-reduction neutralization assay to determine antigen-specific antibody titers and neutralizing antibody titers, respectively. In this study we demonstrate that hens hyperimmunized against the SARS-CoV-2 recombinant S1 and receptor binding domain (RBD) proteins produced neutralizing antibodies against SARS-CoV-2. We further demonstrate that antibody production was dependent on the dose and type of antigen administered. Our data suggests that antibodies purified from the egg yolk of hyperimmunized hens can be used as immunoprophylaxis in humans at risk of exposure to SARS-CoV-2.     

Corneal absorption and anterior chamber pharmacokinetics of dipeptide monoester prodrugs of ganciclovir (GCV): in vivo comparative evaluation of these prodrugs with Val-GCV and GCV in rabbits.

AIM: The overall aim of this study was to evaluate the corneal absorption of dipeptide monoester prodrugs of ganciclovir (GCV) and compare these results with L-valine-GCV and GCV. Another aim was to evaluate the pharmacokinetics of these prodrugs in aqueous humor. METHODS: A well was placed on the cornea of anesthetized New Zealand albino rabbits with linear probes implanted in the aqueous humor. Two hundred microlitres (200 microL) of a 0.43% w/v (saturation concentration) solution of GCV and equimolar concentrations of its prodrugs, VGCV, glycine-valine-GCV (GVGCV), valine-valine-GCV (VVGCV), and tyrosine-valine- GCV (YVGCV), were placed in the corneal well and were allowed to diffuse for a period of 2 h. Subsequently, the drug solution was aspirated and the well removed. Samples were collected every 20 min throughout the infusion and postinfusion phases and were analyzed by high-performance liquid chromatography to determine the aqueous humor concentrations. RESULTS: Area under the concentration time profile (AUC)infinity and maximum concentration (Cmax) of YVGCV were found to be higher than other prodrugs. AUC of total GCV obtained from YVGCV administration was found to be twelvefold more than AUC of GCV and 6.2-fold more than AUC obtained with total GCV from VGCV administration. VVGCV also exhibited 3.2 times higher AUC relative to VGCV. Also, AUC and Cmax of regenerated GCV from YVGCV was 8.6 and 4.9 times more than GCV, respectively. VVGCV did not produce higher concentrations of GCV. Elimination half-life of regenerated GCV from YVGCV administration was observed to be 157 min. CONCLUSIONS: YVGCV and VVGCV exhibited superior corneal absorption and bioavailability, in comparison with GVGCV, VGCV, and GCV. Such facilitated absorption of prodrugs may be a result of a combination of transcellular passive diffusion and peptide transporter (PEPT1)-mediated transport across the corneal epithelium.     

A highly efficient metal oxide incorporated metal organic framework [Nd2O3-MIL(Fe)-88A] for the electrochemical detection of dichlorvos

In this study, a Nd₂O₃@MIL(Fe)-88A composite was prepared through a hydrothermal method and used to detect dichlorvos. The XRD result demonstrated that the prepared sensor is highly crystalline in nature. The affinity of metal oxide and MIL(Fe)-88A could be utilised to overcome low stability and sensitivity owing to their synergistic and electronic effects. Differential pulse voltammetry (DPV) exhibits the electrocatalytic behaviour of Nd₂O₃@MIL(Fe)-88A; it functions at a lower potential at −0.5 to 0.8 V and has a wide linear range of 1–250 nM. It shows a very low detection limit of 0.92 nM with good sensitivity (4.42 mA nM⁻¹) and selectivity. The developed Nd₂O₃@MIL(Fe)-88A sensor was successfully applied to detect dichlorvos in real analysis. The recovery range calculated for cabbage and orange extracts was 96–97% and 99.5–103.4%, respectively, and RSD% calculated for cabbage and orange extracts was from 1.40 to 3.39% and from 0.64 to 2.26%, respectively.

A Nd₂O₃@MIL(Fe)-88A composite was prepared through a hydrothermal method and used to detect dichlorvos.     

Titin activates myosin filaments in skeletal muscle by switching from an extensible spring to a mechanical rectifier

Titin is a molecular spring in parallel with myosin motors in each muscle half-sarcomere, responsible for passive force development at sarcomere length (SL) above the physiological range (>2.7 μm). The role of titin at physiological SL is unclear and is investigated here in single intact muscle cells of the frog (Rana esculenta), by combining half-sarcomere mechanics and synchrotron X-ray diffraction in the presence of 20 μM para-nitro-blebbistatin, which abolishes the activity of myosin motors and maintains them in the resting state even during activation of the cell by electrical stimulation. We show that, during cell activation at physiological SL, titin in the I-band switches from an SL-dependent extensible spring (OFF-state) to an SL-independent rectifier (ON-state) that allows free shortening while resisting stretch with an effective stiffness of ~3 pN nm⁻¹ per half-thick filament. In this way, I-band titin efficiently transmits any load increase to the myosin filament in the A-band. Small-angle X-ray diffraction signals reveal that, with I-band titin ON, the periodic interactions of A-band titin with myosin motors alter their resting disposition in a load-dependent manner, biasing the azimuthal orientation of the motors toward actin. This work sets the stage for future investigations on scaffold and mechanosensing-based signaling functions of titin in health and disease.

Contraction of the striated muscle is powered by the cyclical adenosine triphosphate (ATP)-fueled interactions of the motor protein myosin II, arranged in two bipolar arrays on thick filaments originating at the midpoint of each sarcomere (M-line), with the nearby thin, actin-containing filaments originating at the sarcomere extremities (Z-line, Fig. 1A). In the half-sarcomere, myosin motors are mechanically coupled as parallel force generators and the collective force depends on the number of motors available for actin attachment and thus on the degree of overlap between thick and thin filaments (Fig. 1B, black circles; ref. 1). The half-sarcomere is the basic functional unit in which the emergent properties from the arrays of myosin motors, the interdigitating thin filaments, and a “third” filament made by the cytoskeleton protein titin (Fig. 1C) account for the mechanical performance of muscle and its regulation.Open in a separate windowFig. 1.Structure–function of myofilaments and titin in relation to the length of the sarcomere. (A) Overview of the thick filament (blue), myosin motors (orange), and thin filament (yellow) at SL 2.2 μm (full overlap) and 3.0 μm (partial overlap). (B) Relation between SL and either active force at the plateau of the isometric tetanic contraction (black circles, linear fit to points at SL >2.2 μm, continuous line) or passive force (triangles, fitted with an exponential equation (red dashed line) and with the model (red circles) described in SI Appendix, Supporting Note 1 and Fig. S1). Data from ref. 2. (C) Protein disposition on the thin (yellow) and thick (light blue) filaments in the half-sarcomere at rest at 2.2 μm SL. M-line on the right and Z-line on the left. Inset: Overlap region on an enlarged scale to show with better resolution the ~38 nm axial periodicity of the troponin complex (gray) along the thin filament and the two motor domains (orange) of each myosin molecule tilted back on their tail (blue) in the OFF state (3, 4). The 49 crowns of motors are numbered starting from the M-line; thin filament with tropomyosin (brown) and troponin complex (gray); MyBP-C (green) aligned with myosin triplets from crowns 12 to 30. Titin (magenta) with PEVK segment identified by dark magenta. HBZ, half-bare zone. P-, C-, and D-zones, proximal, MyBP-C containing and distal zones. Only two of the six titin molecules and only one of the three series of MyBP-C molecules per htf are represented for clarity. (D) Straightening of the proximal tandem Ig segment by passive stretch to 3.0 μm SL.Titin is a giant protein (up to 4 MDa) that spans the half-sarcomere (Fig. 1C, magenta), first through the I-band, connecting the Z-line with the tip of the thick filament, and then through the A-band, associated with the thick filament (six molecules per thick filament; refs. 5, 6) up to the M-line at the center of the sarcomere (7–9). The titin I-band region acts as a spring able to transmit the stress also when no myosin motors are attached to actin. In the muscle fiber of the frog, in which there is no contribution from extracellular matrix components (10, 11), titin is responsible for the passive force when the muscle cell is stretched at rest (Fig. 1B, triangles; refs. 12–16). Within the I-band titin, the distal tandem immunoglobulin-like segment forms a stiff end-filament composed of the six titin molecules attaching to the tip of the thick filament (17, 18), while the other two segments account for titin extensibility: the proximal tandem Ig segment (hereinafter called tandem Ig segment) and the unique sequence rich in proline (P), glutamate (E), valine (V), and lysine (K) residues (PEVK segment). Both spring-like segments exhibit variable muscle-type specific lengths (7, 19), which account for the differences in passive force–sarcomere length (SL) relations (20). In situ studies using immunofluorescence and immunoelectron microscopy on skinned fibers and myofibrils from mammalian skeletal muscle demonstrated that the large extensibility of the muscle sarcomere at SL < 2.7 μm is enabled by straightening out of randomly bent elements of the tandem Ig segment. At longer SL, at which the tandem Ig segment approaches its contour length, the passive force increases more steeply, reflecting the PEVK segment stiffness (SI Appendix, Supporting Note 1 and Fig. S1; see refs. 21–25).Titin in the A-band is composed of Ig and fibronectin (Fn) domains each ~4 nm long, with two distinct domain superrepeats: 11 “C-type” superrepeats, each composed of 11 Ig-Fn domains, extending from about layer 3 to 37 of the myosin crowns, and 6 “D-type” superrepeats, each composed of seven Ig-Fn domains, extending from about layer 38 to the filament tip (Fig. 1C; refs. 7, 26–28). The A-band region of titin is made inextensible by its association to the other proteins in the thick filament, myosin, and the Myosin Binding Protein C (MyBP-C), an accessory protein that is bound with its C terminus to the central one-third of the half-thick filament (htf) (C-zone, from layer 12 to 30, Fig. 1C) and extends from the thick filament backbone to establish dynamic interactions with the thin filament (2, 29–31) with its N terminus.I-band titin transmits any pulling force exerted on the extremity of the half-sarcomere to the tip of the thick filament and in this way could play a role in thick filament mechanosensing that switches myosin motors ON (3, 32). Moreover, as an elastic element in parallel with motors, I-band titin could preserve the homogeneity of sarcomeres during contraction, by preventing the lengthening of weak half-sarcomeres. However, titin-dependent passive force typically rises steeply only at SL > 2.6 µm (Fig. 1B; refs. 2, 10, 11, 22, 24, 33), and thus I-band titin stiffness is too low for the above functions at physiological SL, unless it gets much larger during contraction.The mechanical definition of the I-band titin in situ in the active half-sarcomere is hampered by the presence of the in-parallel array of myosin motors with a stiffness that is more than one order of magnitude larger than titin stiffness (34). Here, we use para-nitro-blebbistatin (PNB; ref. 35) to inhibit actin–myosin interaction during tetanic stimulation of a frog muscle cell. In addition, 20 μM PNB suppresses in vitro actin-triggered ATPase activity of frog muscle myosin S1 and heavy meromyosin (HMM) (SI Appendix, Materials and Methods and Fig. S2 A and B) and the mechanical response of the muscle cell to tetanic stimulation (SI Appendix, Fig. S2 C–E), maintaining the motors in the OFF-state conformation, in which they lie tilted back on the surface of the thick filament (Fig. 1C and SI Appendix, Fig. S3) (4, 36). Previous studies noted that blebbistatin does not fully suppress the mechanical response and maintain the motor OFF-state upon Ca²⁺ activation in skinned rabbit psoas fibers (32, 37). This is likely a consequence of either the lower inhibitory power of blebbistatin as compared to PNB (SI Appendix, Fig. S2 A and B) or intrinsic limits of skinned preparations to fully preserve the motor OFF-structure (27, 38).Here, we used sarcomere-level mechanics and small-angle X-ray fiber diffraction to determine the titin-dependent mechanical and structural responses to a stepwise increase in load imposed on the muscle cell under PNB-inhibitory conditions. Length changes in units of nanometer per half-sarcomere (hereinafter referred to as nm) were measured with a striation follower in a population of ~500 sarcomeres. We discovered that upon stimulation at physiological SL, titin in the I-band switches from the OFF-state characterized by large extensibility to the ON-state in which it exhibits rectifying properties, allowing free shortening, while opposing stretching with a viscosity coefficient three orders of magnitude larger that underpins an effective stiffness of 3 pN nm⁻¹. With the I-band titin in the ON-state, the periodic interactions between A-band titin and myosin motors are able to activate the thick filament by perturbing the resting disposition of motors on the surface of the thick filament in a load-dependent manner and biasing them toward the sixfold rotational symmetry of the thin filaments in the myofilament lattice.