Intramuscular Pressure of Human Tibialis Anterior Muscle Reflects in vivo Muscular Activity

Intramuscular pressure (IMP) is the fluid hydrostatic pressure generated within a muscle and reflects the mechanical forces produced by a muscle. By providing accurate quantification of interstitial fluid pressure, the measurement of IMP may be useful to detect changes in skeletal muscle function not identified with established techniques. However, the relationship between IMP and muscle activity has never been studied in vivo in healthy human muscles. To determine if IMP is able to evaluate electromechanical performance of muscles in vivo, we tested the following hypotheses on the human tibialis anterior (TA) muscle: (i) IMP increases in proportion to muscle activity as measured by electrical [Compound Muscle Action Potential (CMAP)] and mechanical (ankle torque) responses to activation by nerve stimulation and (ii) the onset delay of IMP (IMPD) is shorter than the ankle torque electromechanical delay (EMD). Twelve healthy adults [six females; mean (SD) = 28.1 (5.0) years old] were recruited. Ankle torque, TA IMP, and CMAP responses were collected during maximal stimulation of the fibular nerve at different intensity levels of electrical stimulation, and at different frequencies of supramaximal stimulation, i.e., at 2, 5, 10, and 20 Hz. The IMP response at different stimulation intensities was correlated with the CMAP amplitude (r² = 0.94). The area of the IMP response at different stimulation intensities was also significantly correlated with the area of the CMAP (r² = 0.93). Increasing stimulation intensity resulted in an increase of the IMP response (P < 0.001). Increasing stimulation frequency caused torque (P < 0.001) as well as the IMP (P < 0.001) to increase. The ankle torque EMD [median (interquartile range) = 41.8 (14.4) ms] was later than the IMPD [33.0 (23.6) ms]. These findings support the hypotheses and suggest that IMP captures active mechanical properties of muscle in vivo and can be used to detect muscular changes due to drugs, diseases, or aging.

Delafloxacin meglumine for the treatment of acute bacterial skin and skin structure infections (ABSSSI)

Delafloxacin meglumine (Baxdela, WQ-3034, ABT-492, RX-3341; Melinta Therapeutics) was approved by the U.S. Food and Drug Administration (FDA) in June 2017 for the treatment of acute bacterial skin and skin structure infections on the basis of data from two phase III trials. Delafloxacin is a broad-spectrum anionic fluoroquinolone and its distinct chemical structure increases its potency in acidic environments. It is known to inhibit DNA replication and repair by targeting DNA gyrase and topoisomerase IV. Delafloxacin is administered via both oral and parenteral routes. It has potent activity against methicillin-resistant Staphylococcus aureus and Streptococci, and is also effective against Enterobacteriaceae and Pseudomonas aeruginosa. Delafloxacin is currently in phase III evaluation for treatment of community-acquired pneumonia and was classified as a qualified infectious disease product by the U.S. FDA in its approval.

Cutaneous complications associated with breast augmentation: A review

Breast augmentation is one of the most popular and safe cosmetic procedures performed by plastic surgeons worldwide. Although breast implants are available in a number of different materials, silicone-filled implants remain the most common type. However, prior to the development of breast implants, various materials were injected into the soft tissues of the breasts to increase breast volume, which caused cutaneous complications and disfigurement. This review details the history of breast augmentation, the current methods used in augmentation surgery, and associated cutaneous complications.

Outcome of the modified Lapidus procedure for hallux valgus deformity during the first year following surgery: A prospective clinical and gait analysis study

BACKGROUND

The modified Lapidus procedure is a surgical option to treat moderate to severe hallux valgus deformity with good radio-clinical outcome. However, comprehensive biomechanical outcome evaluation of this surgery at mid-term follow-up is missing. This study assesses and compares the radio-clinical and gait outcome at 6 and 12 months following modified Lapidus procedure.

METHOD

Ten consecutive female patients with moderate to severe hallux valgus who underwent modified Lapidus procedure participated in the study. Comprehensive gait assessment was performed preoperatively, at 6 and 12 months postoperatively. Gait parameters including spatiotemporal, kinematics and plantar pressure were analyzed using pressure insoles and 3-dimensional inertial sensors. Outcome was evaluated using two clinical questionnaires, i.e. the American Orthopaedic Foot and Ankle Score and the Foot and Ankle Ability Measure, and X-rays.

FINDINGS

Three spatiotemporal, two kinematics, and seven plantar pressure parameters significantly improved between 6 months and 12 months postoperatively. Significant improvement in radiological and clinical outcome was reported at 6 and 12 months. The Foot and Ankle Ability Measure showed non-significant improvement at 12 months.

INTERPRETATION

The outcome of this study is consistent with the previously reported good clinical and radiological results at one year following Lapidus for moderate to severe hallux valgus. Twelve gait parameters demonstrated that outcome improves from 6 months to 12 months postoperative with room for further improvement at long term. The gait outcome in this study confirms the longer rehabilitation period following modified Lapidus procedure. Studies with a larger sample size are required to confirm these findings.

Genotypic and Pathogenic Diversity of Colletotrichum sublineola Isolates from Sorghum (Sorghum bicolor) and Johnsongrass (S. halepense) in the Southeastern United States

Anthracnose caused by Colletotrichum sublineola is an important disease of cultivated sorghum (Sorghum bicolor) worldwide. Anthracnose is also common on the ubiquitous wild sorghum relative Johnsongrass (S. halepense). Analysis of repetitive molecular fingerprinting markers revealed that isolates of C. sublineola from both hosts in the southeastern United States were genotypically diverse, with relatively few haplotypes found in more than one location. With few exceptions, isolates recovered from S. bicolor belonged to a population that was genetically distinct from the population recovered from S. halepense. Twenty-three isolates from cultivated sorghum were all pathogenic to at least one of 13 heritage inbred lines of S. bicolor. In all, 4 of 10 isolates from S. halepense were also pathogenic to one or more of the lines, while the rest caused no disease in greenhouse assays. The four pathogenic isolates from S. halepense were less aggressive, on average, than isolates from S. bicolor, although the ranges overlapped. Pathogenicity tests involving 15 representative pathogenic isolates from S. bicolor and S. halepense on eight heritage inbred lines of S. bicolor identified 12 races. The combined results of this study demonstrated that C. sublineola comprises two separate host-associated subpopulations in the field, even though some isolates from S. halepense were able to cause disease on S. bicolor under ideal greenhouse conditions. Nonetheless, the apparent existence of infrequent cross-infection events in the field, indicated by molecular fingerprinting, suggests that Johnsongrass has the potential to serve as a refuge and an incubator for genetic diversity in C. sublineola, which can complicate efforts to develop and deploy resistant sweet sorghum varieties in the region.

Intramuscular Pressure of Tibialis Anterior Reflects Ankle Torque but Does Not Follow Joint Angle-Torque Relationship

Intramuscular pressure (IMP) is the hydrostatic fluid pressure that is directly related to muscle force production. Electromechanical delay (EMD) provides a link between mechanical and electrophysiological quantities and IMP has potential to detect local electromechanical changes. The goal of this study was to assess the relationship of IMP with the mechanical and electrical characteristics of the tibialis anterior muscle (TA) activity at different ankle positions. We hypothesized that (1) the TA IMP and the surface EMG (sEMG) and fine-wire EMG (fwEMG) correlate to ankle joint torque, (2) the isometric force of TA increases at increased muscle lengths, which were imposed by a change in ankle angle and IMP follows the length-tension relationship characteristics, and (3) the electromechanical delay (EMD) is greater than the EMD of IMP during isometric contractions. Fourteen healthy adults [7 female; mean (SD) age = 26.9 (4.2) years old with 25.9 (5.5) kg/m² body mass index] performed (i) three isometric dorsiflexion (DF) maximum voluntary contraction (MVC) and (ii) three isometric DF ramp contractions from 0 to 80% MVC at rate of 15% MVC/second at DF, Neutral, and plantarflexion (PF) positions. Ankle torque, IMP, TA fwEMG, and TA sEMG were measured simultaneously. The IMP, fwEMG, and sEMG were significantly correlated to the ankle torque during ramp contractions at each ankle position tested. This suggests that IMP captures in vivo mechanical properties of active muscles. The ankle torque changed significantly at different ankle positions however, the IMP did not reflect the change. This is explained with the opposing effects of higher compartmental pressure at DF in contrast to the increased force at PF position. Additionally, the onset of IMP activity is found to be significantly earlier than the onset of force which indicates that IMP can be designed to detect muscular changes in the course of neuromuscular diseases impairing electromechanical transmission.

Delamanid for the treatment of pulmonary multidrug-resistant tuberculosis

Out of a handful of new drugs currently in clinical trials for the treatment of tuberculosis, delamanid, a nitro-dihydro-imidazole derivative, has successfully emerged. Delamanid is a novel mycolic acid biosynthesis inhibitor that is equally potent against drug-sensitive as well as drug-resistant Mycobacterium tuberculosis. One of the strongest points for delamanid is its inability to be metabolized by cytochrome P450 enzymes, making it a promising candidate to be used in combination therapies for the treatment of tuberculosis and HIV. Additionally, it has successfully completed phase II efficacy trials and has received conditional marketing authorization from the European Medicines Agency.

Obstructive Sleep Apnea Dynamically Increases Nocturnal Plasma Free Fatty Acids, Glucose, and Cortisol During Sleep

CONTEXT

Obstructive sleep apnea (OSA) is associated with diabetes and cardiovascular disease. This association may be related to metabolic changes that transpire during sleep in OSA.

OBJECTIVE

To examine the impact of OSA, elicited by cessation of continuous positive airway pressure (CPAP), on frequently sampled nocturnal metabolic markers including plasma free fatty acids (FFAs), glucose, insulin, triglycerides (TGs), cortisol, and lactate, as well as glucose production, oral glucose tolerance, blood pressure (BP), endothelial function, cholesterol, and high-sensitivity C-reactive protein (hsCRP).

DESIGN AND SETTING

Randomized crossover trial of CPAP vs CPAP withdrawal.

PATIENTS

Thirty-one patients with moderate to severe OSA acclimated to CPAP.

INTERVENTION

Patients underwent attended polysomnography while sleeping with therapeutic CPAP, or after CPAP withdrawal, in random order. Venous blood was sampled at ∼20-minute intervals on both nights. In 11 patients, we assessed glucose kinetics with an infusion of 6,6-[2H2]glucose.

RESULTS

CPAP withdrawal caused recurrence of OSA associated with hypoxemia, sleep disruption, and heart rate (HR) elevation. CPAP withdrawal dynamically increased nocturnal FFA (P = 0.007), glucose (P = 0.028), and cortisol (P = 0.037), in proportion to respiratory event frequency, HR elevation, or sleep fragmentation. Diabetes predisposed to glucose elevation. CPAP withdrawal also increased systolic BP (P = 0.017) and augmentation index (P = 0.008), but did not affect insulin, TGs, glucose production, oral glucose tolerance, cholesterol, or hsCRP.

CONCLUSION

OSA recurrence during CPAP withdrawal increases FFA and glucose during sleep, associated with sympathetic and adrenocortical activation. Recurring exposure to these metabolic changes may foster diabetes and cardiovascular disease.

Aggressiveness of Colletotrichum sublineola Strains from Sorghum bicolor and S. halepense to Sweet Sorghum Variety Sugar Drip, and Their Impact on Yield

Sweet sorghum (Sorghum bicolor) has been grown in the southeastern United States for more than 150 years on a relatively limited scale, primarily for forage and for the production of table syrup. However, interest in the crop has increased recently due to its potential as a feedstock for biofuels. Colletotrichum sublineola is the causal agent of anthracnose on cultivated sorghum and on the wild sorghum relative Johnsongrass (S. halepense). Anthracnose is an important disease of grain sorghum worldwide, but little is known about its impact on sweet sorghum in the U.S. The aggressiveness of four C. sublineola isolates collected from sweet and grain sorghum and from Johnsongrass at various locations across Kentucky was measured as disease incidence and severity on the susceptible heirloom sweet sorghum inbred Sugar Drip in inoculated field trials. The isolate from sweet sorghum was the most aggressive, while the two Johnsongrass isolates caused only minimal disease symptoms. Disease incidences of up to 99%, and severities of up to 16.7% of leaf area affected, had no negative effect on the yield of biomass, grain, juice, or Brix. Removal of sorghum seed heads increased Brix in the stalks and leaves, but did not affect susceptibility to anthracnose. The same group of fungal isolates was evaluated for aggressiveness in greenhouse assays on juvenile plants, and in the laboratory on seedlings and detached leaf sheaths. These protocols will be useful for prescreening sorghum germplasm for new sources of resistance or for characterizing the aggressiveness of new fungal isolates.

Muscle activation pattern during gait and stair activities following total hip arthroplasty with a direct anterior approach: a comprehensive case study

Muscle activation following total hip arthroplasty with a direct anterior approach has not previously been reported in the literature. This case report details the electromyography outcome of a 60-year-old male patient with unilateral direct anterior approach-total hip arthroplasty during walking and stair activities. Outcome reports the continuation of altered muscle activation 12 months postoperatively, even with a good clinical outcome.

Qualitative analysis of foot intersegment coordination in the sagittal plane following surgery for end-stage ankle osteoarthrosis

Today, ankle joint kinematic assessment gives important information regarding the intersegment range of motion. It does not, however, provide information regarding coordination between the segments. This study aimed to determine whether or not intersegment coordination can provide valuable, otherwise missed information in relation to kinematic alterations of the ankle joint. The study consisted of 40 participants, including 12 total ankle replacement (TAR) patients, 12 ankle arthrodesis (AA) patients, and 16 controls. Gait assessment was carried out wearing 3-D inertial sensors. Intersegment coordination was determined by calculation of the continuous relative phase (CRP) between foot intersegments. CRP analysis found useful information regarding the magnitude and directionality of segment motion throughout the gait cycle, with AA patients reporting an altered coordination pattern for all three intersegments, forefoot-hindfoot, hindfoot-shank, and forefoot-shank, and TAR patients showing alterations in the hindfoot-shank intersegment. Results show that assessment of intersegment coordination can provide further information, otherwise overlooked by the general kinematic assessment, which could be used to optimize patient rehabilitation. Furthermore, the study showed that such information could be used to compare surgical outcomes. As a result, the study concludes that the inclusion of intersegment coordination assessment could be beneficial in clinical practice. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1304-1310, 2017.