Spectral Analysis for Circadian Rhythms: A Perspective on Theory, History and Practice | Chapter 5 | Mathematics and Computer Science: Contemporary Developments Vol. 3

The present study highlights maximum entropy spectral analysis for circadian rhythms. These periodicities are studied in systems ranging from intracellular fluorescence to complex behaviors such as running wheel activity; data acquisition and format vary accordingly. There is an array of numerical techniques available to estimate the period of circadian and other biological rhythms. When selecting a method, one must consider factors such as resilience to stochastic noise, sensitivity to weak rhythms, resolution of numerous periodicities or signals embedded in noise, and accuracy in measuring periods. Maximum Entropy Spectral Analysis (MESA) has proven itself excellent in all regards. The MESA algorithm fits an autoregressive model to the data and extracts the spectrum from its coefficients. MESA has proven itself superior to standard Fourier analysis as it does not produce artifacts resulting from the various manipulations needed absent a model for the function. Both resolution and sidelobe suppression are also superior to standard Fourier analysis. Entropy in this context refers to "ignorance" of the data and since this is formally maximized, no unwarranted assumptions are made. Computationally, the coefficients are calculated efficiently by the solution of the Yule-Walker equations in an iterative algorithm. MESA is compared here to other common techniques. It is normal to remove high-frequency noise from time series using digital filters before analysis. The Butterworth filter is demonstrated here and a danger inherent in multiple filtering passes is discussed.

 

Author(s) Details

Harold B Dowse
Department of Mathematics and Statistics, School of Biology and Ecology, 5751 Murray Hall, University of Maine, Orono ME 04469, USA.

 

Please see the book here:- https://doi.org/10.9734/bpi/mcscd/v3/1586

Anticonvulsant Profile of the Enantiomers of DL- HEPP-In-vitro and In-vivo Study | Chapter 8 | Pharmaceutical Science: New Insights and Developments Vol. 2

Aims: Epilepsy is a brain disorder that is characterized by recurrent seizures. It affects 1% of the global population and remains poorly managed in 30% of patients despite available antiepileptic drugs, which often cause significant side effects even in controlled cases, highlighting the urgent need for improved treatments. In this paper, the resolution of DL-HEPP and the anticonvulsant activity and neurotoxicity of its enantiomers, as candidates for the treatment of refractory epilepsy, were reported.

Study Design: Synthesis of DL-HEPP, separation of enantiomers (+)-HEPP and (-)-HEPP, and anticonvulsant profile and neurotoxicity of DL-HEPP and its enantiomers.

Place and Duration of Study: This study was done at the Biochemistry, Pharmacy and Organic Chemistry Departments, Escuela Nacional de Ciencias Biológicas del Instituto Politécnico Nacional, Mexico City. The duration of the study is from 2012 to 2017.

Methodology: In order to investigate differences in biological activity between HEPP enantiomers, the racemate was resolved using (-) brucine and (+) phenylethylamine salts of the acids. The optically active acids were esterified with diazomethane and reacted with ammonia to yield (+)-HEPP and (-)-HEPP. Enantiomeric purity was confirmed (>99% ee) using proton magnetic resonance with Europium tris-[3-(trifluoromethylhydroxymethylene)-(+)camphorate] and chiral HPLC. The anticonvulsant activity of DL-HEPP and its enantiomers was tested in pentylenetetrazole (PTZ), β-mercaptopropionic acid (β-MPA), bicuculline (BIC), thiosemicarbazide (TSC), and maximal electroshock (MES) seizure models. The rotarod ataxia test was used to evaluate neurotoxicity. Time-to-peak drug effects were established prior to dose-response studies. The duration of the anticonvulsant activity (+) and (-) HEPP was evaluated.

Results: Chiral HPLC confirmed enantiomeric purity (>99% ee) for HEPP enantiomers. ¹H and ¹³C-NMR spectra revealed identical chemical shifts for DL-HEPP and its enantiomers, the addition of Eu[TFH-cam-d] highlighted the stereochemical differences. DL-HEPP and its enantiomers exhibited a similar significant anticonvulsant activity in several acute seizure models in mice in nontoxic doses. Compounds DL-HEPP, (+) HEPP y (-) HEPP showed protective indexes (PI: 3.85, 3.66 and 4.14 respectively) outperforming sodium valproate (PI= 3.16) in the PTZ test. Neurotoxicity was comparable among DL-HEPP enantiomers. Over time, (-) HEPP maintained the highest protection, while the anticonvulsant activity of (+) HEPP declined rapidly against PTZ-induced seizures.

Conclusion: At the time of peak drug effect (30 min), there are no differences either in the anticonvulsant activity against PTZ, BIC, TSC and β-MPA-induced seizures or in neurotoxicity between DL-HEPP and its enantiomers, which suggests that the optical resolution of DL-HEPP is not necessary for further preclinical studies. The protection of DL-HEPP and its enantiomers against convulsant drugs that block GABA neurotransmission suggests that they act in the GABAergic system. The research with enantiomers of HEPP provides valuable insights for the development of more effective and safer antiepileptic therapies.

 

Author (s) Details

Ana L. Ambriz-Hernandez
Departamento de Bioquímica, Escuela Nacional de Ciencias Biológicas del Instituto Politécnico Nacional, Prol. Carpio y Plan de Ayala s/n Col. Plutarco Elías Calles, México 11340, Mexico.

 

José G. Cervantes-Espinoza
Departamento de Bioquímica, Escuela Nacional de Ciencias Biológicas del Instituto Politécnico Nacional, Prol. Carpio y Plan de Ayala s/n Col. Plutarco Elías Calles, México 11340, Mexico.

 

Eugenia Vargas-Fernández
Departamento de Bioquímica, Escuela Nacional de Ciencias Biológicas del Instituto Politécnico Nacional, Prol. Carpio y Plan de Ayala s/n Col. Plutarco Elías Calles, México 11340, Mexico.

 

Amelia de la Cruz-Marín
Departamento de Bioquímica, Escuela Nacional de Ciencias Biológicas del Instituto Politécnico Nacional, Prol. Carpio y Plan de Ayala s/n Col. Plutarco Elías Calles, México 11340, Mexico.

 

José G. Buendía-Pazarán
Departamento de Bioquímica, Escuela Nacional de Ciencias Biológicas del Instituto Politécnico Nacional, Prol. Carpio y Plan de Ayala s/n Col. Plutarco Elías Calles, México 11340, Mexico.

 

Javier Esquivel-Vargas
Departamento de Bioquímica, Escuela Nacional de Ciencias Biológicas del Instituto Politécnico Nacional, Prol. Carpio y Plan de Ayala s/n Col. Plutarco Elías Calles, México 11340, Mexico.

 

Alexis G. Góngora-Úbeda
Departamento de Bioquímica, Escuela Nacional de Ciencias Biológicas del Instituto Politécnico Nacional, Prol. Carpio y Plan de Ayala s/n Col. Plutarco Elías Calles, México 11340, Mexico.

 

Javier Peralta-Cruz
Departamento de Química Orgánica, Escuela Nacional de Ciencias Biológicas del Instituto Politécnico Nacional, Prol. Carpio y Plan de Ayala s/n Col. Plutarco Elías Calles, México 11340, Mexico.

 

Germán Chamorro-Cevallos
Departamento de Farmacia. Escuela Nacional de Ciencias Biológicas del Instituto Politécnico Nacional, Prol. Carpio y Plan de Ayala s/n Col. Plutarco Elías Calles, México 11340, Mexico.

 

Sergio E. Meza-Toledo
Departamento de Bioquímica, Escuela Nacional de Ciencias Biológicas del Instituto Politécnico Nacional, Prol. Carpio y Plan de Ayala s/n Col. Plutarco Elías Calles, México 11340, Mexico.

 

Please see the book here:- https://doi.org/10.9734/bpi/psnid/v2/4118 

Hyphenated Technique - Thermogravimetry-Differential Scanning Colorimetry Coupled to Mass Spectroscopy| Chapter 4 | Research Highlights in Science and Technology Vol. 4

 A thermo-examining approach which is known as thermogravimetric reasoning uses weight changes that occur whena sample is warmed to a consistent pace to confirm a material thermal balance & percentage of the doubtful additives present. DSC analysis is secondhand for measuringa variety of quantities, including softening temperature, hidden melting warmth, melding warmth, reaction capacity, and many more.Mass spectrophotometry is a potent analytical finish containing abundant uses in the biomedical & pharmaceutical industries. A maneuver's increased sensitivity and judgment have opened up new avenues for the test of prescribed medications and complex basic structure metabolites. The synthetic properties and thermal balance of plant-based polymers isolated from chemically singular soils were revealed using thermogravimetry as well DSC, quadrupole mass spectrometry, and added techniques. TGA/DSC, when used together along with MS, isolates several ions from the pattern substitute in accordance with a specific bulk-to-charge ratio.The connected instrument is used to evaluate the powder covering's physical characteristics and shame balance while also identifying basic components.

Author(s) Details:

K. Bhavyasri,
Department of Pharmaceutical Analysis, RBVRR Women’s College of Pharmacy, Barkatpura, Hyderabad-500027, India.

Please see the link here: https://stm.bookpi.org/RHST-V4/article/view/10910

Effective Elimination of Analog Impairments Error in Parallel Interleaving Sigma Delta A/D Converters: A Recent Study | Chapter 5 | New Approaches in Engineering Research Vol. 7

 Oversampling sigma delta modulators that produce one bit samples of input signals can be utilised to make AD converters that can produce multi bit samples with high resolution but low sampling frequency, or poor resolution samples with high sampling frequency. Using numerous converters running in parallel in a time interleaved manner is one approach of overcoming this limitation. The resolution of the converter's digital output can be greatly increased in this manner, reducing the quantising error value. However, parallel converters' analogue flaws induce modulation of the output samples, which can significantly deteriorate the converter's capabilities. Many articles detailing different architectures of Σ-Δ AD converters limit their analysis to the frequency domain, ignoring the fact that Σ-Δ modulators are synchronous voltage to frequency converters. This paper shows how, by understanding the time domain properties of Σ-Δ modulators, the problem of analogue converter impairments can be overcome, resulting in a better design of high resolution Σ-Δ AD converters.

Author (s) Details

Tadeusz Sidor
University of Occupational Safety Management in Katowice, Poland.

View Book :- https://stm.bookpi.org/NAER-V7/article/view/2224