Adaptation of muscle fibre types and capillary network to acute denervation and shortlasting reinnervation

We postulated that, in rat extensor digitorum longus muscle (EDL), the length of capillaries per fibre surface area (Lcap/Sfib) and per fibre volume (Lcap/Vfib) could reflect fibre-type transformations accompanied by changes in oxidative metabolic profile and selective fibre-type atrophy. We excised rat EDL muscle 2 weeks after the sciatic nerve was cut (acute denervation; DEDL) and 4 weeks after the nerve was crushed (early reinnervation; REDL) and characterised muscle fibre-type transformation by the expression of myosin heavy-chain isoforms and by succinate dehydrogenase (SDH) and nicotinoamide adenine dinucleotide-tetrazolium reductase (NADH-TR) reactions. The numerical percentage (N/N) and area percentage (A/A) of pure and hybrid fibres and their diameter were determined, as was the A/A of SDH- and NADH-TR-positive fibres. The length of capillaries per fibre length (Lcap/Lfib), Lcap/Sfib and Lcap/Vfib were estimated in REDL and Lcap/Vfib in DEDL. In DEDL, the type 2x and 2b fibres evidently atrophied, with the N/N of type 2x fibres being lower and that of hybrid fibres higher. In REDL, the N/N of hybrid fibres was even higher, consequent to a lower N/N of type 2b fibres; however, fibre diameters approached values of the control EDL. Compared with control EDL, denervated and reinnervated muscles exhibited a higher A/A of oxidative fibres. This is probably the result of fibre-type transformation and selective fibre atrophy. We conclude that capillary length does not change during acute denervation and early reinnervation. The obtained higher values of Lcap/Sfib and Lcap/Vfib are related to changes in muscle fibre cross-sectional area. This study was supported by the Slovenian Research Agency and the Ministry of Education, Youth and Sport of the Czech Republic (KONTAKT grant no. 9-06-6 and grant no. LC06063).     

The number of satellite cells in slow and fast fibres from human vastus lateralis muscle

The aim of this investigation was to study the distribution of satellite cells in slow (type I fibres) and fast (type II fibres) fibres from human vastus lateralis muscle. This muscle is characterised by a mixed fibre type composition and is considered as the site of choice for biopsies in research work and for clinical diagnosis. Biopsy samples were obtained from five healthy young volunteers and a total of 1,747 type I fibres and 1,760 type II fibres were assessed. Satellite cells and fibre type composition were studied on serial muscle cross-sections stained with specific monoclonal antibodies. From a total of 218 satellite cells, 116 satellite cells were found in contact with type I fibres (53.6±8% of the satellite cells associated to type I fibres) and 102 satellite cells in contact with type II fibres (46.4±8% of the satellite cells associated to type II fibres). There was no significant difference (P=0.4) between the percentages of satellite cells in contact with type I and with type II fibres. Additionally, there was no relationship between the mean number of satellite cells per fibre and the mean cross-sectional area of muscle fibres. In conclusion, our results show that there is no fibre type-specific distribution of satellite cells in a human skeletal muscle with mixed fibre type composition.     

On the use of hybrid reinforcement learning for autonomic resource allocation

Reinforcement Learning (RL) provides a promising new approach to systems performance management that differs radically from standard queuing-theoretic approaches making use of explicit system performance models. In principle, RL can automatically learn high-quality management policies without an explicit performance model or traffic model, and with little or no built-in system specific knowledge. In our original work (Das, R., Tesauro, G., Walsh, W.E.: IBM Research, Tech. Rep. RC23802 (2005), Tesauro, G.: In: Proc. of AAAI-05, pp. 886–891 (2005), Tesauro, G., Das, R., Walsh, W.E., Kephart, J.O.: In: Proc. of ICAC-05, pp. 342–343 (2005)) we showed the feasibility of using online RL to learn resource valuation estimates (in lookup table form) which can be used to make high-quality server allocation decisions in a multi-application prototype Data Center scenario. The present work shows how to combine the strengths of both RL and queuing models in a hybrid approach, in which RL trains offline on data collected while a queuing model policy controls the system. By training offline we avoid suffering potentially poor performance in live online training. We also now use RL to train nonlinear function approximators (e.g. multi-layer perceptrons) instead of lookup tables; this enables scaling to substantially larger state spaces. Our results now show that, in both open-loop and closed-loop traffic, hybrid RL training can achieve significant performance improvements over a variety of initial model-based policies. We also find that, as expected, RL can deal effectively with both transients and switching delays, which lie outside the scope of traditional steady-state queuing theory.

Evidences for the existence of two steps in DNA replication obtained in toluene-treated Escherichia coli.

Toluene-treated Escherichia coli can synthesize DNA in the presence of precursors and ATP [Moses, R.E. & Richardson, C.C. (1970) Proc. Natl Acad. Sci. U.S.A. 67, 674--681]. The replacement of ATP by another NTP or dNTP leads to the premature arrest of the reaction. Residual synthesis in the presence of an NTP or dNTP other than ATP differs from the complete reaction in the presence of ATP because it is less sensitive to nalidixic acid and novobiocin and because its maximal activity can be obtained with lower concentrations of dNTP or shorter times of toluene treatment. However, like the complete reaction, residual synthesis occurs at the replication fork pre-existing in vivo at the time of toluenization, produces short and long pieces of DNA, is inhibited by arabinosyl-adenine triphosphate, azide or mitomycin C, and is dependent on the dnaE, DNAB and dnaG gene products. We conclude from these data that ATP is specifically required for a step in DNA replication which involves the activity of DNA gyrase, the target of nalidixic acid and novobiocin [Higgins, N.P., Peebles, C.L., Sugino, A. & Cozzarelli, N.R. (1978) Proc. Natl Acad. Sci. U.S.A. 75, 1773-1777]. In the absence of DNA gyrase activity, short DNA pieces are formed and sealed but only a limited amount of the chromosome can be replicated (residual synthesis). In the presence of DNA gyrase activity, DNA synthesis can occur on a longer portion of the chromosome (complete synthesis).     

The assembly of ionic currents in a thalamic neuron. III. The seven-dimensional model

We replace our earlier three-dimensional ha-model of a thalamic neuron (Rose & Hindmarsh, Proc. R. Soc. Lond. B 237, 289-312 (1989b)) by a seven-dimensional ha-model. The stability and state diagrams for this seven-dimensional model are shown to be similar to those of the three-dimensional system with which it is compared. Two examples that illustrate how the seven-dimensional model can be related to experimental recordings are then discussed in detail. In each case we show the state and stability diagrams and the time courses of the different ionic currents during the burst response. We discuss how the various components of the state diagram could be determined experimentally. These experiments are illustrated by using our model to simulate the results of actual experiments. Finally the state and stability diagrams are transferred to a current-voltage diagram. This shows the advantage of the state diagram compared with the current-voltage diagram for representing the dynamics of the firing of a thalamic neuron.     

Contributions to Physiology of the Antenna-Heart in Periplaneta americana (L.) (Blattodea: Blattidae)

An accessory pulsatile organ of an open circulatory system in insects supplying the antennae with haemolymph was investigated. The rhythm of this so-called antenna-heart is generated by a myogenic automatism and can be neuronally influenced via the nervus cardioantennalis.The action potentials of the muscle fibres show typical pre-depolarization and mostly no overshoot. A specific membrane resistance (R(m)) of about 660Omegacm(-2) was calculated for the fibres. Some electrical coupling between the muscle fibres is presumed for synchronization of any myogenically triggered heart beat which could actually be proved experimentally by current injection in the antenna-heart. However, intercalated disks or gap junctions could not be found. Nevertheless, a good coupling factor (U(2)/U(1)) between all fibres was demonstrated by parallel recordings and can be well described by a conductance model according to fibre topology.     

Structural and functional recovery of electropermeabilized skeletal muscle in-vivo after treatment with surfactant poloxamer 188

A critical requirement for cell survival after trauma is sealing of breaks in the cell membrane [M. Bier, S.M. Hammer, D.J. Canaday, R.C Lee, Kinetics of sealing for transient electropores in isolated mammalian skeletal muscle cells, Bioelectromagnetics 20 (1999) 194-201; R.C. Lee, D.C. Gaylor, D. Bhatt, D.A. Israel, Role of cell membrane rupture in the pathogenesis of electrical trauma, J. Surg. Res. 44 (1988) 709-719; R.C. Lee, J.F. Burke, E.G. Cravalho (Eds.), Electrical Trauma: The Pathophysiology, Manifestations, and Clinical Management, Cambridge University Press, 1992; B.I. Tropea, R.C. Lee, Thermal injury kinetics in electrical trauma, J. Biomech. Engr. 114 (1992) 241-250; F. Despa, D.P. Orgill, J. Newalder, R.C Lee, The relative thermal stability of tissue macromolecules and cellular structure in burn injury, Burns 31 (2005) 568-577; T.A. Block, J.N. Aarsvold, K.L. Matthews II, R.A. Mintzer, L.P. River, M. Capelli-Schellpfeffer, R.L. Wollman, S. Tripathi, C.T. Chen, R.C. Lee, The 1995 Lindberg Award. Nonthermally mediated muscle injury and necrosis in electrical trauma, J. Burn Care and Rehabil. 16 (1995) 581-588; K. Miyake, P.L. McNeil, Mechanical injury and repair of cells, Crit. Care Med. 31 (2003) S496-S501; R.C. Lee, L.P. River, F.S. Pan, R.L. Wollmann, Surfactant-induced sealing of electropermeabilized skeletal muscle membranes in vivo, Proc. Natl. Acad. Sci. 89 (1992) 4524-4528; J.D. Marks, C.Y. Pan, T. Bushell, W. Cromie, R.C. Lee, Amphiphilic, tri-block copolymers provide potent membrane-targeted neuroprotection, FASEB J. 15 (2001) 1107-1109; B. Greenebaum, K. Blossfield, J. Hannig, C.S. Carrillo, M.A. Beckett, R.R. Weichselbaum, R.C. Lee, Poloxamer 188 prevents acute necrosis of adult skeletal muscle cells following high-dose irradiation, Burns 30 (2004) 539-547; G. Serbest, J. Horwitz, K. Barbee, The effect of poloxamer-188 on neuronal cell recovery from mechanical injury, J. Neurotrauma 22 (2005) 119-132]. The triblock copolymer surfactant Poloxamer 188 (P188) is known to increase the cell survival after membrane electroporation [R.C. Lee, L.P. River, F.S. Pan, R.L. Wollmann, Surfactant-induced sealing of electropermeabilized skeletal muscle membranes in vivo, Proc. Natl. Acad. Sci. 89 (1992) 4524-4528; Z. Ababneh, H. Beloeil, C.B. Berde, G. Gambarota, S.E. Maier, R.V. Mulkern, Biexponential parametrization of T2 and diffusion decay curves in a rat muscle edema model: Decay curve components and water compartments, Magn. Reson. Med. 54 (2005) 524-531]. Here, we use a rat hind-limb model of electroporation injury to determine if the intravenous administration of P188 improves the recovery of the muscle function. Rat hind-limbs received a sequence of either 0, 3, 6, 9, or 12 electrical current pulses (2 A, 4 ms duration, 10 s duty cycle). Magnetic resonance imaging (MRI) analysis, muscle water content and compound muscle action potential (CMAP) amplitudes were compared. Electroporation injury manifested edema formation and depression of the CMAP amplitudes. P188 (one bolus of 1 mg/ml of blood) was administrated 30 or 60 min after injury. Animals receiving P188 exhibited reduced tissue edema (p < 0.05) and increased CMAP amplitudes (p < 0.03). By comparison, treatment with 10 kDa neutral dextran, which produces similar serum osmotic effects as P188, had no effect on post-electroporation recovery. Noteworthy, the present results suggest that a single intravenous dose of P188 is effective to restore the structural integrity of damaged tissues with intact circulation.     

Gramicidin cation channel: an experimental determination of the right-handed helix sense and verification of beta-type hydrogen bonding

Due to the difficulty of obtaining protein/lipid cocrystals for diffraction studies, structural research on intrinsic membrane proteins and polypeptides has been largely restricted to indirect experimental techniques. Hence, many fundamental questions associated with peptide/lipid systems remain unanswered. In particular, the handedness of the gramicidin A transmembrane ion channel incorporated into lipid bilayers has been an open question for nearly two decades. In this study, solid-state 15N NMR spectroscopy is employed to probe directly the secondary structure of the polypeptide backbone. Recent determinations of the 15N chemical shift anisotropy tensor with respect to the molecular frame enable the quantitative evaluation of the 15N chemical shift resonances obtained from oriented dimyristoylphosphatidylcholine (DMPC) bilayer samples containing specific site 15N labeled gramicidin. This direct structural approach verifies the beta-sheet hydrogen-bonding pattern proposed by Urry [Urry, D. W. (1971) Proc. Natl. Acad. Sci. U.S.A. 68, 672-676] and determines that in our DMPC bilayer preparations the gramicidin channel is right-handed. Additional structural information is provided by the 15N chemical shift data in the form of orientational constraints on the C alpha-C alpha axis orientation of individual peptides relative to the helix axis. The significance of these solid-state NMR results lies in the direct determination of the helix sense and the verification of the beta-type hydrogen bonding, in the development of the solid-state NMR methods for obtaining such information, and in emphasizing the importance of having direct structural data at atomic resolution.     

Spectral and time domain characteristics of single muscle fibre action potentials during continuous activity extracted from model considerations

A model of the muscle fibre extracellular action potentials (ECAPs) calculation using experimentally recorded intracellular action potentials (ICAPs) has been applied to investigate the effect of repetitive stimulation on the electrical activity of isolated frog muscle fibres. The ECAPs were calculated both at small (0.01 mm) and at large (5 mm) radial distances to the fibre axis, and their relationship with the original ICAP parameters has been inferred. Fourier transformation of the calculated ECAPs in order to obtain the spectral characteristics and to trace out their behaviour during continuous fibre activity was performed. Stimulation frequency dependence on the ECAP time characteristics and on the shift of the maximum spectral density towards low frequencies at small and large radial distance were observed. The spectral density peak frequency is propagation velocity (PV)-dependent. The advantage of the presented method over the available experimental extracellular recording techniques from isolated muscle fibers is the possibility to show the effect of continuous muscle fibre activity on the parameters of the ECAPs and their spectral characteristics at large radial distance, which is not experimentally accessible. Our results are in agreement with those experimentally obtained. The results from the model prove the role of changes in PV of excitation along the muscle fibres (representing the last link in the complex organized motor system) in the development of fatigue. Received: 24 July 1997 / Accepted in revised form: 2 July 1998     

Multivariate classification of histochemically stained human skeletal muscle fibres by the SIMCA method

Summary The SIMCA (soft independent modelling of class analogy) method of pattern recognition has been used to classify four muscle fibre types: I, IIA, IIB and IIC. The samples were histochemically stained human skeletal sections from biopsy material. Disjoint (separate) class modelling gave information about variables, i.e., the combinations of alkaline, acidic and Ca²⁺-containing preincubation procedures with appropriate discrimination power, and showed satisfactory separation of the classes (fibre types). Two serial stained muscle sections represent a minimum for a proper classification of the four fibre groups. A comparison of biopsy samples from two different persons showed significant variation in the data structure between similar fibre types, probably caused by intermuscle variations. It is suggested that the introduction of computer-assisted classification by the application of such multivariate analytical techniques both facilitates the classification of muscle fibres and improves the precision and reliability of fibre typing.     

The claw closer muscle of two estuarine crab species,Cyrtograpsus angulatus and Neohelice granulata (Grapsoidea,Varunidae): histochemical fibre type composition

Longo, M.V. and Díaz, A.O. (2011). The claw closer muscle of two estuarine crab species, Cyrtograpsus angulatus and Neohelice granulata (Grapsoidea, Varunidae): histochemical fibre type composition. —Acta Zoologica (Stockholm) 00 : 1–7. This study permitted the characterization of four types of muscle fibres in the claw closer muscles of Cyrtograpsus angulatus and Neohelice granulata. Succinic dehydrogenase (SDH) for mitochondria, periodic acid Schiff (PAS) for glycogen, Sudan Black B for lipids and myosin‐adenosine triphosphatase (m‐ATPase) preincubated at alkaline and acid pHs were used for that purpose. The mean fibre diameters, the relative areas and frequencies of each muscle fibre type were calculated. Types I and IV would be considered ‘extreme’ groups with type I fibres large, weak and acid/alkaline‐labile m‐ATPase, weak SDH, PAS and Sudan, and type IV fibres small, very strong and acid/alkaline‐resistant m‐ATPase, strong SDH and PAS, and moderate Sudan. Types II and III would belong to a predominant ‘intermediate’ group. Type IV fibres were scarce in C. angulatus but represented 25% of the total fibre population in N. granulata. In C. angulatus, the relative area occupied by type I fibres was bigger than its relative proportion, whereas in N. granulata, types I and II had similar patterns. Concluding, variations in fibre type composition in the claw closer muscles of C. angulatus and N. granulata would be linked to different habitats and feeding behaviours.     

Re-Evaluation of Sarcolemma Injury and Muscle Swelling in Human Skeletal Muscles after Eccentric Exercise

The results regarding the effects of unaccustomed eccentric exercise on muscle tissue are often conflicting and the aetiology of delayed onset muscle soreness (DOMS) induced by eccentric exercise is still unclear. This study aimed to re-evaluate the paradigm of muscular alterations with regard to muscle sarcolemma integrity and fibre swelling in human muscles after voluntary eccentric exercise leading to DOMS. Ten young males performed eccentric exercise by downstairs running. Biopsies from the soleus muscle were obtained from 6 non-exercising controls, 4 exercised subjects within 1 hour and 6 exercised subjects at 2–3 days and 7–8 days after the exercise. Muscle fibre sarcolemma integrity, infiltration of inflammatory cells and changes in fibre size and fibre phenotype composition as well as capillary supply were examined with specific antibodies using enzyme histochemistry and immunohistochemistry. Although all exercised subjects experienced DOMS which peaked between 1.5 to 2.5 days post exercise, no significant sarcolemma injury or inflammation was detected in any post exercise group. The results do not support the prevailing hypothesis that eccentric exercise causes an initial sarcolemma injury which leads to subsequent inflammation after eccentric exercise. The fibre size was 24% larger at 7–8 days than at 2–3 days post exercise (p<0.05). In contrast, the value of capillary number per fibre area tended to decrease from 2–3 days to 7–8 days post exercise (lower in 5 of the 6 subjects at 7–8 days than at 2–3 days; p<0.05). Thus, the increased fibre size at 7–8 days post exercise was interpreted to reflect fibre swelling. Because the fibre swelling did not appear at the time that DOMS peaked (between 1.5 to 2.5 days post exercise), we concluded that fibre swelling in the soleus muscle is not directly associated with the symptom of DOMS.     

Constitutive Expression of Yes-Associated Protein (Yap) in Adult Skeletal Muscle Fibres Induces Muscle Atrophy and Myopathy

The aim of this study was to investigate the function of the Hippo pathway member Yes-associated protein (Yap, gene name Yap1) in skeletal muscle fibres in vivo. Specifically we bred an inducible, skeletal muscle fibre-specific knock-in mouse model (MCK-tTA-hYAP1 S127A) to test whether the over expression of constitutively active Yap (hYAP1 S127A) is sufficient to drive muscle hypertrophy or stimulate changes in fibre type composition. Unexpectedly, after 5–7 weeks of constitutive hYAP1 S127A over expression, mice suddenly and rapidly lost 20–25% body weight and suffered from gait impairments and kyphosis. Skeletal muscles atrophied by 34–40% and the muscle fibre cross sectional area decreased by ≈40% when compared to control mice. Histological analysis revealed evidence of skeletal muscle degeneration and regeneration, necrotic fibres and a NADH-TR staining resembling centronuclear myopathy. In agreement with the histology, mRNA expression of markers of regenerative myogenesis (embryonic myosin heavy chain, Myf5, myogenin, Pax7) and muscle protein degradation (atrogin-1, MuRF1) were significantly elevated in muscles from transgenic mice versus control. No significant changes in fibre type composition were detected using ATPase staining. The phenotype was largely reversible, as a cessation of hYAP1 S127A expression rescued body and muscle weight, restored muscle morphology and prevented further pathological progression. To conclude, high Yap activity in muscle fibres does not induce fibre hypertrophy nor fibre type changes but instead results in a reversible atrophy and deterioration.     

Effects of electrical stimulation upon post-hatching development of fibre types in normally innervated fast and slow latissimus dorsii muscles of the chicken

In chicken, the main characteristic properties of muscle fibre types in slow anterior (ALD) and fast posterior (PLD) latissimus dorsii are acquired during post-hatching development. At day 4 it becomes possible to distinguish between alpha' and beta' fibre types in ALD muscle. At the same time, mATPase staining and NADH-TR activity permit recognition of alpha w and alpha R fibres within PLD muscle. During further development, muscle fibre typology progressively changes towards the adult slow and fast type. Chronic stimulation at a slow rhythm (5 Hz) of PLD prevents the change in relative proportions of alpha R and alpha W fibres within the muscle that occurs in normal post-hatching development and increases the number of beta R fibres. Moreover, oxidative activity is increased in all muscle fibre types following stimulation. In ALD muscle, chronic stimulation at a fast rhythm (40 Hz) results in a decrease in oxidative activity and inhibits the differentiation of alpha' and beta' muscle fibre types. This study demonstrates that in young chicken, the pattern of activity influences the differenciation of fibre types in slow and fast muscles.     

Metabolism of threonine in newborn infants

Threonine kinetics, threonine oxidative pathway, and the relationship between threonine and whole body protein turnover were quantified in 10 healthy term infants during the first 48 h after birth. The kinetic data were obtained 6 h after the last feed (fasting) and in response to formula feeding, using [U-(13)C(4),(15)N]threonine, [(2)H(5)]phenylalanine, and [(15)N]glycine tracers. The rate of carbon dioxide production (Vco(2)) and (13)C enrichment of the expired CO(2) were measured to quantify the rate of oxidation of threonine. The rate of appearance (R(a)) of threonine (136 +/- 37 micromol.kg(-1).h(-1)) was higher in newborn infants than that reported in adults. Formula feeding resulted in a significant decrease in threonine R(a) (P < 0.05). A significant positive correlation was seen between phenylalanine R(a) and threonine R(a), both during fasting and after formula feeding (r(2) = 0.65). In contrast to a 1:1 ratio of threonine and phenylalanine in mixed muscle protein, threonine R(a) relative to phenylalanine R(a) was 2.2 +/- 0.4. The fractional rate of threonine flux oxidized was 20% during fasting and 26% (P < 0.05) in response to nutrient administration. There was a significant correlation between plasma threonine concentration and threonine oxidation (r(2) = 0.75). No measurable incorporation of threonine in plasma glycine was seen. These data suggest that threonine is exclusively degraded by the glycine-independent serine/threonine dehydratase pathway. A higher flux of threonine relative to phenylalanine indicates higher turnover of threonine enriched proteins.     

Development of image analysis tool for the classification of muscle fibre type using immunohistochemical staining

An accurate characterisation of muscle fibres is essential for studying muscle plasticity. During some transient events such as ageing, myogenesis, physical activity or conversion of muscle to meat, the morphological parameters and/or the fibre type distribution may change. Nowadays, this information is generally obtained using immunohistology techniques, but these analyses are acknowledged to be laborious and time-consuming. In fact, each myofibre, from thousands, must be measured individually and its expression profile in response to different anti-myosin antibodies must be established step by step. In this paper, we describe a new histological approach using double-labelling (laminin, myosin) serial sections, fluorescence microscopy visualisation and, finally, semi-automatic image analysis. The goal of the study was to propose a tool allowing faster fibre type characterisation, including the identification of hybrid fibres from pure ones. The steps in the image processing prone to subjectivity have been fully automated. On the other hand, the expert retained control of all image analysis procedures requiring visual diagnosis. The tool that we developed with the Visilog software allowed a rapid and objective fibre typing and morphometric characterisation of two different bovine muscles. The results were in agreement with our previous histological and densitometric assays. The method and the tool proved to be potentially more efficient than other techniques used in our institute or described in the literature. A more global evaluation will be considered in other laboratories as well as on other animal species.     

Characterization of Grating Coupled Surface Plasmon Polaritons Using Diffracted Rays Transmittance

A method to sense the excitation of surface plasmon polariton (SPP) on metallic grating device using the transmitted signal will be presented. The grating transmittance signal will be fully characterized varying the light incident angle and azimuthal grating orientation by means of the SPP vector model and rigorous coupled-wave analysis simulation. Simulation results will be compared with experimental measurements obtained with a 635 nm wavelength laser in the transverse magnetic polarization mode. The laser will light grating devices in contact with either air or water through a customized microfluidic chamber. A characterization of the diffracted rays will show the relationship between the grating coupling configuration and the Kretschmann one. In fact, the diffracted ray affected by SPP resonance is transmitted with an output angle which is the same incident angle that should be used to excite SPP in Kretschmann configuration. Lastly, the grating parameters (amplitude and metal thickness) impact on transmittance signal will be analyzed with respect to the order zero reflectance signal.