Anatomic Location of the Tongue Base Neurovascular Bundle

Knowledge of the location of the hypoglossal/lingual artery neurovascular bundle (HLNVB) is essential in performing tongue base resections for neoplasm and for obstructive sleep apnea. Transoral and transcervical resections of the tongue base may be performed with greater exposure and certainty when the relationship of the HLNVB to local landmarks is understood; knowledge of the HLNVB allows resection of a larger amount of contralateral tongue base during partial glossectomy without violating the contralateral remnant tongue's blood supply. Ten cadaver heads were dissected to determine the position of the HLNVB with respect to soft tissue and bony landmarks at the tongue base. Our results indicate the position of the tongue base HLNVB is significantly inferior and lateral, that is, 2.7 cm inferior and 1.6 cm lateral to the foramen cecum, 0.9 cm superior to the hyoid bone, and 2.2 cm medial to the mandible. This inferolateral location allows the potential for aggressive tongue base resection without neurovascular compromise.     

Endoscopic KTP-532 laser assisted diverticulotomy for Zenker's diverticulum

Zenker's diverticulum, though counnon in western countries is uncommon in India. This diverticuham is an extension of umcosa through Killian's dehiscence. Various surgical methods have been described for the treatment of this condition including the use of lasers but none in Indian Journals. In this paper we describe a case of Zenker's diverticulum where diverticulotomy using KTP532 laser was successfully performed. Its advantages over other techniques are mentioned.     

Visual impairment and refractive errors in school children in Andhra Pradesh,India

Purpose:Addressing childhood vision impairment (VI) is one of the main goals of the World Health Organization’s (WHO) combating blindness strategies. The primary aim of this study was to estimate the prevalence of VI, causes, and its risk factors in school children in Krishna district, Andhra Pradesh, India.Methods:Children aged 4–15 years were screened in schools using the 6/12 Snellen optotype by trained community eye health workers, and those who failed the test and those reported or found to have obvious eye conditions were referred to primary (VC), secondary (SC), or tertiary (TC) care centre appropriately, where they underwent a complete eye examination including cycloplegic refraction and fundus examination.Results:A total of 56,988 children were screened, of whom 51.18% were boys. The mean age was 9.69 ± 3.26 years (4–15 years). Overall, 2,802/56,988 (4.92%) children were referred to a VC, of which 632/56,988 (1.11%) required referral to SC/TC. PVA of <6/12 was found in 1.72% (95% confidence interval [CI]: 1.61–1.83). The prevalence of refractive error (corrected and uncorrected) was 2.38% (95% CI: 2.26–2.51) and myopia was 2.17% (95% CI: 2.05–2.29). In multivariable analysis, older children, those in urban schools, private schools, and children with a disability had an increased risk of VI and myopia. Additionally, the risk of myopia was higher among girls than boys. Of those referred and reached SC/TC, 73.64% were due to avoidable causes.Conclusion:Childhood VI prevalence was 1.72% in this region. Uncorrected refractive error (URE) was the major cause of VI in children. Older age, schools in urban locations, private schools, and the presence of disability were associated with the risk of VI among children.     

Effects of Sand-Based Plyometric-Jump Training in Combination with Endurance Running on Outdoor or Treadmill Surface on Physical Fitness in Young Adult Males

This study aimed at examining the effects of nine weeks of sand-based plyometric-jump training (PJT) combined with endurance running on either outdoor or treadmill surface on measures of physical fitness. Male participants (age, 20.1 ± 1.7 years) were randomly assigned to a sand-based PJT combined with endurance running on outdoor surface (OT, n = 25) or treadmill surface (TT, n = 25). The endurance running intervention comprised a mixed training method, i.e., long slow distance, tempo, and interval running drills. A control group was additionally included in this study (CG, n = 25). Participants in CG followed their regular physical activity as OT and TT but did not receive any specific intervention. Individuals were assessed for their 50-m linear sprint time, standing long jump (SLJ) distance, cardiorespiratory fitness (i.e., Cooper test), forced vital capacity (FVC), calf girth, and resting heart rate (RHR). A three (groups: OT, TT, CG) by two (time: pre, post) ANOVA for repeated measures was used to analyze the exercise-specific effects. In case of significant group-by-time interactions, Bonferroni adjusted paired (within-group) and independent (between-group comparisons at post) t-tests were used for post-hoc analyses. Significant group-by-time interactions were found for all dependent variables (p < 0.001 – 0.002, ɳ_p² = 0.16 – 0.78). Group-specific post-hoc tests showed improvements for all variables after OT (p < 0.001, Hedges’g effect size [g] = 0.05 – 1.94) and TT (p < 0.001, g = 0.04 – 2.73), but not in the CG (p = 0.058 – 1.000, g = 0.00 – 0.34). Compared to CG, OT showed larger SLJ (p = 0.001), cardiorespiratory fitness (p = 0.004), FVC (p = 0.008), and RHR (p < 0.001) improvements. TT showed larger improvements in SLJ (p = 0.036), cardiorespiratory fitness (p < 0.001), and RHR (p < 0.001) compared with CG. Compared to OT, TT showed larger improvements for SLJ (p = 0.018). In conclusion, sand-based PJT combined with either OT or TT similarly improved most measures of physical fitness, with greater SLJ improvement after TT. Coaches may use both concurrent exercise regimes based on preferences and logistical constrains (e.g., weather; access to treadmill equipment). Key points

• Concurrent training in the form of sand-based plyometric-jump training and endurance running exercise can enhance physical fitness in young individuals;
• Compared to treadmill running, rating of perceived exertion was higher in outdoor running sessions;
• Sand-based plyometric-jump training may induce greater standing long jump performance when combined with endurance running on treadmill surface as compared to outdoor surface.

Key words: Muscle strength, musculoskeletal and neural physiological phenomena, movement, resistance training, high-intensity interval training, exercise     

Competing interactions give rise to two-state behavior and switch-like transitions in charge-rich intrinsically disordered proteins

The most commonly occurring intrinsically disordered proteins (IDPs) are polyampholytes, which are defined by the duality of low net charge per residue and high fractions of charged residues. Recent experiments have uncovered nuances regarding sequence–ensemble relationships of model polyampholytic IDPs. These include differences in conformational preferences for sequences with lysine vs. arginine and the suggestion that well-mixed sequences form a range of conformations, including globules, conformations with ensemble averages that are reminiscent of ideal chains, or self-avoiding walks. Here, we explain these observations by analyzing results from atomistic simulations. We find that polyampholytic IDPs generally sample two distinct stable states, namely, globules and self-avoiding walks. Globules are favored by electrostatic attractions between oppositely charged residues, whereas self-avoiding walks are favored by favorable free energies of hydration of charged residues. We find sequence-specific temperatures of bistability at which globules and self-avoiding walks can coexist. At these temperatures, ensemble averages over coexisting states give rise to statistics that resemble ideal chains without there being an actual counterbalancing of intrachain and chain-solvent interactions. At equivalent temperatures, arginine-rich sequences tilt the preference toward globular conformations whereas lysine-rich sequences tilt the preference toward self-avoiding walks. We also identify differences between aspartate- and glutamate-containing sequences, whereby the shorter aspartate side chain engenders preferences for metastable, necklace-like conformations. Finally, although segregation of oppositely charged residues within the linear sequence maintains the overall two-state behavior, compact states are highly favored by such systems.

Significant fractions of eukaryotic proteomes are made up of intrinsically disordered regions (IDRs) (1). Conformational heterogeneity (2) is a defining hallmark of IDRs (3–5). Studies over the past decade have helped quantify relationships (6) that connect sequence-encoded information within IDRs to properties of conformational ensembles such as overall sizes and shapes, the amplitudes of spontaneous conformational fluctuations, and the dynamics of interconverting between distinct conformational states (7–19). These sequence–ensemble relationships have direct functional consequences that have been uncovered via studies based on biophysical, biochemical, and engineering approaches (5, 20–38). Our work, which is focused on physical principles underlying sequence–ensemble relationships of IDRs, is of direct relevance to understanding how IDRs function.Charged residues are key determinants of sequence–ensemble relationships of IDRs (19, 39–41). They contribute through highly favorable free energies of hydration (42) and long-range electrostatic interactions. Net charge per residue (19, 39, 40) and the patterning of oppositely charged residues (43–45) are useful order parameters for describing sequence–ensemble relationships and interactions of charge-rich IDRs (46). Both features can be modulated through posttranslational modifications (47–51), charge renormalization by solution ions (52), and charge regulation through context- and conformation-dependent uptake and release of protons (53).Polyampholytes feature roughly equivalent numbers of oppositely charged residues, and they make up more than 70% of known IDRs (7, 17). For a given amino acid composition, which sets the fraction of charged residues and the net charge per residue, it has been shown that the linear mixing vs. segregation of oppositely charged residues can have a profound impact on sequence–ensemble relationships of polyampholytic IDRs (31, 32, 43). Specifically, for a given set of solution conditions, sequences featuring uniform linear distributions of oppositely charged residues are predicted to favor more expanded conformations compared to sequences with identical amino acid compositions where the oppositely charged residues are segregated into distinct blocks along the linear sequence. These predictions made using simulation and theory (43, 44, 54) have been confirmed using different experiments (31–33, 41, 55).The ensemble-averaged radii of gyration (R_g) of flexible polymers follow scaling relationships of the form R_g ∼ N^ν. Here, N denotes the number of residues and the scaling exponent ν is a measure of the length scale over which conformational fluctuations are correlated. For homopolymers or systems that are effective homopolymers, ν has four limiting values, viz., 0.33, 0.5, 0.59, or 1, corresponding to globules, Flory random coils (FRCs), self-avoiding walks, and rod-like conformations, respectively (56). Atomistic simulations performed at fixed temperatures suggest that ν ≈ 0.59 (43) for strong, well-mixed polyampholytes (17). The explanation for this behavior is as follows. Electrostatic attractions and repulsions are realized on similar length scales for well-mixed sequences. These interactions screen one another, and the highly favorable free energies of hydration become the main determinants of overall sizes and shapes of well-mixed strong polyampholytes (17). In contrast, compact conformations are formed by strong polyampholytes where oppositely charged residues are segregated into distinct blocks. Here, the electrostatic attractions between oppositely charged blocks can outcompete opposing effects of favorable solvation. These inferences were gleaned using sequences comprising 1:1 ratios of Lys and Glu (43). In the original simulations, the reference free energies of hydration of all charged residues were treated as being quantitatively equivalent and highly favorable. This leads to the hypothesis that Lys and Arg are interoperable with one another as determinants of sequence–ensemble relationships of IDRs (17). A similar inference emerges regarding the interoperability of Asp and Glu with respect to one another. The recent work of Sørensen and Kjaergaard has challenged these inferences (57). Using a system where model IDRs were deployed as flexible linkers between interaction domains, Sørensen and Kjaergaard used their measurements to estimate the relationships between amino acid sequence and the scaling exponent ν (57). Inferences from their experiments suggest that the ν ≈ 0.33 for (GRESRE)_n and ν ≈ 0.5 for (GKESKE)_n for the specific conditions they used in their measurements. Here, n is the number of repeats of the hexapeptides GRESRE or GKESKE. The results point to significant differences between Arg- and Lys-containing sequences. Further, while globularity of (GRESRE)_n has precedent in mean-field theories for polyampholytes, the mechanism by which FRC-like behavior of (GKESKE)_n is achieved is unclear. Here, we develop a plausible physical explanation for the findings of Sørensen and Kjaergaard (57). Our work is based on atomistic simulations and the ABSINTH implicit solvation model and forcefield paradigm (58–61).     

Characterizing the Mechanical Behavior of Bone and Bone Surrogates in Compression Using pQCT

Many axial and appendicular skeleton bones are subjected to repetitive loading during daily activities. Until recently, the structural analysis of fractures has been limited to 2D sections, and the dynamic assessment of fracture progression has not been possible. The structural failure was analyzed using step-wise micro-compression combined with time-lapsed micro-computed tomographic imaging. The structural failure was investigated in four different sample materials (two different bone surrogates, lumbar vertebral bodies from bovine and red deer). The samples were loaded in different force steps based on uniaxial compression tests. The micro-tomography images were used to create three-dimensional models from which various parameters were calculated that provide information about the structure and density of the samples. By superimposing two 3D images and calculating the different surfaces, it was possible to precisely analyze which trabeculae failed in which area and under which load. According to the current state of the art, bone mineral density is usually used as a value for bone quality, but the question can be raised as to whether other values such as trabecular structure, damage accumulation, and bone mineralization can predict structural competence better than bone mineral density alone.