Assessment of prescribing pattern of drugs and completeness of prescriptions as per the World Health Organization prescribing indicators in various Indian tertiary care centers: A multicentric study by Rational Use of Medicines Centers-Indian Council of Medical Research network under National Virtual Centre Clinical Pharmacology activity.

OBJECTIVE: The rational use of medicines as per the World Health Organization (WHO) should be practiced globally. However, data regarding the completeness of the prescriptions and their rational use is lacking from developing countries like India. Thus, the aim of this study was to assess the prescribing patterns of drugs and completeness of prescriptions as per WHO core drug use and complementary indicators to provide real-life examples for the Indian Council of Medical Research (ICMR) online prescribing skill course for medical graduates. METHODS: Prescriptions of the patients, fulfilling inclusion criteria, attending Outpatient Departments of various specialties of tertiary care hospitals, were collected by thirteen ICMR Rational use of medicines centers located in tertiary care hospitals, throughout India. Prescriptions were evaluated for rational use of medicines according to the WHO guidelines and for appropriateness as per standard treatment guidelines using a common protocol approved by local Ethics committees. RESULTS: Among 4838 prescriptions, an average of about three drugs (3.34) was prescribed to the patients per prescription. Polypharmacy was noted in 83.05% of prescriptions. Generic drugs were prescribed in 47.58% of the prescriptions. Further, antimicrobials were prescribed in 17.63% of the prescriptions and only 4.98% of prescriptions were with injectables. During the prescription evaluation, 38.65% of the prescriptions were incomplete due to multiple omissions such as dose, duration, and formulation. CONCLUSION: Most of the parameters in the present study were out of the range of WHO-recommended prescribing indicators. Therefore, effective intervention program, like training, for the promotion of rational drug use practice was recommended to improve the prescribing pattern of drugs and the quality of prescriptions all over the country.

How particle-particle and liquid-particle interactions govern the fate of evaporating liquid marbles.

Liquid marbles refer to droplets that are covered with a layer of non-wetting particles. They are observed in nature and have practical significance. These squishy objects bounce, coalesce, break, inflate, and deflate while the liquid does not touch the substrate underneath. Despite the considerable cross-disciplinary interest and value of the research on liquid marbles, a unified framework for describing the mechanics of deflating liquid marbles-as the liquid evaporates-is unavailable. For instance, analytical approaches for modeling the evaporation of liquid marbles exploit empirical parameters that are not based on liquid-particle and particle-particle interactions. Here, we have combined complementary experiments and theory to fill this gap. To unentangle the contributions of particle size, roughness, friction, and chemical make-up, we investigated the evaporation of liquid marbles formed with particles of sizes varying over 7 nm-300 µm and chemical compositions ranging from hydrophilic to superhydrophobic. We demonstrate that the potential final states of evaporating liquid marbles are characterized by one of the following: (I) constant surface area, (II) particle ejection, or (III) multilayering. Based on these insights, we developed an evaporation model for liquid marbles that takes into account their time-dependent shape evolution. The model fits are in excellent agreement with our experimental results. Furthermore, this model and the general framework can provide mechanistic insights into extant literature on the evaporation of liquid marbles. Altogether, these findings advance our fundamental understanding of liquid marbles and should contribute to the rational development of technologies.

Myths, facts and scope of spinal cord tolerance dose revision in Intensity modulated SIB treatment of locally advanced head and neck cancer: A dosimetrical and radiobiological demonstration.

PURPOSE: To explore the possibility of revising the spinal cord tolerance dose in Simultaneously Integrated Boost (SIB) intensity modulated treatment plan of locally advanced head and neck (H&N) cancer and assessment of achieved planning gain due to the revision. In SIB regimen, the Organ at Risk (OARs) tolerance dose is equally distributed throughout the treatment. Clinicians have usually considered the spinal cord tolerance to be the same as in conventional technique. However, in SIB fractionation regimen with intensity modulation treatment, the spinal cord may receive a physical dose of 45Gy, with much lesser dose per fraction than 2Gy per fraction. So when the dose of spinal cord is distributed throughout the treatment, the tolerance dose limit of physical dose can be considered higher than the usual conventional dose limits. In this study, an attempt has been made to explore the possibilities of dose escalation and treatment planning benefits while exploiting this "Window of Opportunity (WoO)" of increase in spinal cord and Planning Risk Volume (PRV) spinal cord tolerance dose. MATERIAL AND METHODS: A total of 12 patients CT data set along with approved structure set of H&N cancer used for treatment planning in. Three independent SIB VMAT plans named as SPC, SPR and SPDE were generated for the 12 patients. First plan (SPC) was generated by considering standard spinal cord tissue constraint of maximum dose of 45Gy and PRV spinal cord maximum dose 50Gy as per QUANTEC summary and second plan (SPR) was generated considering spinal cord tissue constraint of maximum dose 52.50Gy and PRV spinal cord maximum dose 56.35Gy while optimization and dose calculation. The objectives for rest of the Organ at Risk (OAR) were kept same in both the plans during optimization and dose calculation. The SPC plan was copied for creation of third plan (SPDE) in which dose was escalated by increasing dose per fraction for target volumes such that dose to spinal cord reached a maximum dose of 52.50Gy and PRV spinal cord maximum dose of 56.35Gy. In this plan there have been changes to only dose per fraction, however dose optimization and dose calculation have not been performed. Radiobiological parameters TCP and NTCP were also calculated by using indigenously developed software. RESULTS: Considering the increase of spinal cord tolerance dose as "window of opportunity", a sufficient escalation in physical dose, Biological Effective Dose (BED) and Tumor Control Probability (TCP) was observed for all target volumes with acceptable level of NTCP values. CONCLUSION: Sufficient dose escalation and increased in TCP for target volumes or effective planning benefits can be achieved by revising the spinal cord tolerance dose in intensity modulated SIB treatment of locally advanced H&N cancers.

Superhydrophobicity and size reduction enabled Halobates (Insecta: Heteroptera, Gerridae) to colonize the open ocean.

Despite the remarkable evolutionary success of insects at colonizing every conceivable terrestrial and aquatic habitat, only five Halobates (Heteroptera: Gerridae) species (~0.0001% of all known insect species) have succeeded at colonizing the open ocean - the largest biome on Earth. This remarkable evolutionary achievement likely required unique adaptations for them to survive and thrive in the challenging oceanic environment. For the first time, we explore the morphology and behavior of an open-ocean Halobates germanus and a related coastal species H. hayanus to understand mechanisms of these adaptations. We provide direct experimental evidence based on high-speed videos which reveal that Halobates exploit their specialized and self-groomed body hair to achieve extreme water repellence, which facilitates rapid skating and plastron respiration under water. Moreover, the grooming behavior and presence of cuticular wax aids in the maintenance of superhydrophobicity. Further, reductions of their body mass and size enable them to achieve impressive accelerations (~400 ms-2) and reaction times (~12 ms) to escape approaching predators or environmental threats and are crucial to their survival under harsh marine conditions. These findings might also inspire rational strategies for developing liquid-repellent surfaces for drag reduction, water desalination, and preventing bio-fouling.

Comparative study of the synbiotic effect of inulin and fructooligosaccharide with probiotics with regard to the various properties of fermented soy milk.

Numerous combinations of probiotics were explored to find the suitable starter culture for the development of synbiotic soy yoghurt which can give good product characteristics and may be acceptable among consumers. Prebiotics (fructooligosaccharide (FOS) and inulin) were supplemented in an attempt to reduce the after-taste of soymilk, improve acidification profile and growth of probiotics. The addition of prebiotics in soy milk significantly enhanced the acidification rate (10.82 to 23.00 × 10-3 pH units/min) and condensed the fermentation completion time. FOS-supplemented fermented soy milk showed better acidification and post-acidification profile as compared to inulin supplemented samples. The Streptococcus salivarius subsp. thermophilus (ST) - Lactobacillus acidophilus (LA) with FOS gave the better textural properties with firmer gel (350.10), lower adhesiveness (-93.10) and springiness (0.92), higher gumminess (164.50) and average cohesiveness (0.47). FOS-supplemented ST-LA-fermented samples showed good gel characteristics with higher elastic modulus (1672.39 Pa), viscous modulus (416.41 Pa), complex modulus (1723.53 Pa), lower tan δ (14) and higher overall acceptability scores (7.40) on a 9-point hedonic scale. Developed synbiotic soy fermented milk showed more than the 9 log cfu/ml count throughout storage which is required for probiotic functional food.

Comparative analysis of thermal-assisted high pressure and thermally processed mango pulp: Influence of processing, packaging, and storage.

Storage stability and shelf-life of mango pulp packed in three different packaging films and processed using an optimized thermal-assisted high pressure processing treatment 'HPP' (600 MPa/52 ℃/10 min) was analyzed during refrigerated (5 ℃) and accelerated (37 ℃) storage and compared with the conventional thermal treatment 'TT' (0.1 MPa/95 ℃/15 min). After processing, HPP resulted in relatively lower total color difference (3.5), retained higher ascorbic acid (95%), total phenolics (106%), total flavonoids content (118%) in mango pulp compared to TT, with values of 5.0, 62, 83, 73%, respectively. However, HPP led to ∼50% enzymes inactivation (pectin methylesterase, polyphenol oxidase, peroxidase) in comparison to >90% obtained during TT. Both HPP and TT resulted in > 5 log10 units reduction of the studied microorganisms to give a safe product. In contrast to the refrigerated storage, quality changes under accelerated conditions were found to be considerably rapid and dependent on packaging material irrespective of the method of processing. Shelf-life under refrigeration was limited by microbial growth and sensory quality; whereas, browning restricted the shelf-life during accelerated storage. HPP in aluminum-based retort pouch was adjudged superior processing -packaging combination for maximizing the shelf-life of mango pulp to 120 and 58 days during refrigerated and accelerated storage, respectively. In comparison, TT led to higher quality changes upon processing than HPP and resulted in shelf-life of 110 and 58 days under the same packaging and storage conditions, respectively.

Effect of high pressure and thermal processing on spoilage-causing enzymes in mango (Mangifera indica).

The aim of the present work was to model the effect of combined pressure-temperature processing on spoilage-causing enzymes in mango pulp; which conventionally are inactivated using high temperatures leading to inevitable quality losses. The inactivation of enzymes pectin methylesterase (PME), polyphenol oxidase (PPO) and peroxidase (POD) was studied in mango pulp within the pressure, temperature and hold-time ranges of 0.1 to 600MPa, 40 to 70°C and 1s to 90min, respectively. The enzyme inactivation was described as a dual process: initial change in activity during dynamic pressure build-up phase and subsequent decrease under isobaric-isothermal conditions. The former led to considerable increase in activities of all the three enzymes (p<0.05); however, the increased activity reduced with increased intensity of applied pressure-temperature. On the other hand, isobaric-isothermal conditions led to substantial inactivation (p<0.05), with 600MPa/70°C/20min treatment being most effective in reducing the activities of PME, PPO and POD to 32, 15 and 26%, respectively. The enzyme inactivation data was non-linear under isobaric-isothermal conditions and fitted to the nth-order reaction model, indicative of the occurrence of series of reactions possibly due to pressure-temperature interaction effects. The estimated reaction order 'n' was 0.815, 1.106 and 1.137 for PME, PPO and POD, respectively. The estimated reaction rate constant k (min-1) depicted PME to be the most baroresistant enzyme followed by POD and PPO. Temperature and pressure dependency of k was expressed in terms of activation energy and activation volume using the Arrhenius- and Eyring-type relations, respectively. An empirical model with good correlation between actual and predicted data (R2>0.90) was proposed to simulate the rate of enzyme inactivation under isobaric-isothermal conditions as a function of pressure and temperature.

Fourier Transform Near-Infrared Spectroscopy for rapid and simple determination of phytic acid content in green gram seeds (Vigna radiata).

The feasibility of measuring phytic acid content in green gram (Vigna radiata) seeds was investigated by Fourier Transform Near-Infrared (FT-NIR) spectroscopic technique. Pure phytic acid standards of varying concentrations were scanned using FTNIR spectroscopy. The spectra were measured in diffused reflectance mode by keeping 100-1500 mg/100g standard of pure phytic acid in small sample cuvette. A calibration model was developed using pure phytic acid standards of varying concentrations in the near-infrared region (4000-12,000 cm(-1)). FT-NIR spectroscopy with chemometrics, using the first derivative plus vector normalisation method could predict the phytic acid content in green gram seeds samples. The developed model was validated using cross-validation technique. Maximum coefficient of determination (R(2)) value of 0.97 was obtained for the calibration model developed. The developed model was applied to predict phytic acid content in green gram seeds samples within 1-2 min. The developed procedure was further validated by recovery studies by comparing with UV spectroscopic method of phytic acid determination.

Interaction Between Domperidone and Ketoconazole: Toward Prediction of Consequent QTc Prolongation Using Purely In Vitro Information.

We aimed to investigate the application of combined mechanistic pharmacokinetic (PK) and pharmacodynamic (PD) modeling and simulation in predicting the domperidone (DOM) triggered pseudo-electrocardiogram modification in the presence of a CYP3A inhibitor, ketoconazole (KETO), using in vitro-in vivo extrapolation. In vitro metabolic and inhibitory data were incorporated into physiologically based pharmacokinetic (PBPK) models within Simcyp to simulate time course of plasma DOM and KETO concentrations when administered alone or in combination with KETO (DOM+KETO). Simulated DOM concentrations in plasma were used to predict changes in gender-specific QTcF (Fridericia correction) intervals within the Cardiac Safety Simulator platform taking into consideration DOM, KETO, and DOM+KETO triggered inhibition of multiple ionic currents in population. Combination of in vitro-in vivo extrapolation, PBPK, and systems pharmacology of electric currents in the heart was able to predict the direction and magnitude of PK and PD changes under coadministration of the two drugs although some disparities were detected.

Genetic polymorphisms of CYP2E1 and GSTM1 loci and susceptibility to anti-tuberculosis drug-induced hepatotoxicity.

BACKGROUND: Host genetic factors that influence predisposition to anti-tuberculosis drug-induced hepatotoxicity (DIH) are not clear in the Indian population. OBJECTIVE: To investigate the possible association of DIH with polymorphism at the RsaI site of the 5-prime untranslated region of CYP2E1 and GSTM1 'null' mutations. METHODS: In this prospective study, 113 tuberculosis (TB) patients with DIH and 201 TB patients receiving anti-tuberculosis treatment without developing hepatotoxicity (non-DIH) constituted cases and controls, respectively. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) was performed to analyse genetic polymorphisms of CYP450 2E1 at the RsaI site and 'null' GSTM1 mutations. PCR-RFLP results were compared between 185 non-DIH and 105 DIH patients RESULTS: A high frequency of c1c1 genotypes of CYP2E1 was commonly encountered, and the difference between DIH and non-DIH patients was not significant (75.14% vs. 77.14%). The genotypic distribution of c2c2 was significantly higher in the DIH than in the non-DIH group (4.8% vs. 0.5%, OR 8.58, P = 0.03). However, adjustment for age, sex and serum albumin differences yielded an OR of 2.75, making it non-significant (P = 0.26). Homozygous 'null' mutation frequencies at the GSTM1 gene in DIH and non-DIH patients were observed that were not significantly different (40% and 37%, respectively, P = 0.61). CONCLUSION: RsaI variants of the CYP2E1 gene and GSTM1 'null' mutation were not associated with risk of DIH in a north Indian population.

Stabilization of high temperature hexagonal phase of SrAl2O4 at room temperature: role of ZnO.

Strontium aluminate (SrAl2O4) exhibits a monoclinic structure at room temperature (RT) and transforms to a hexagonal structure at above 650 °C, reported previously in the literature. In this article, we have shown a stable, high temperature hexagonal phase of SrAl2O4 (SAO) at RT by synthesizing a SAO-ZnO composite through a combustion technique. While SAO crystallizes in the monoclinic phase by adding 2.5 wt% of ZnO, a stable hexagonal phase of SAO at RT has been obtained for 20 wt% of ZnO. Further, the hexagonal phase of SAO transforms to a monoclinic phase after increasing the calcination temperature from 700 to 1200 °C. The role of ZnO in determining the structure and photoluminescence properties of these composites are discussed.

Twin screw extrusion of kodo millet-chickpea blend: process parameter optimization, physico-chemical and functional properties.

Kodo millet-chickpea flour blend (70:30) was explored for development of directly expanded snack by twin-screw extrusion. Effect of process parameters like temperature (80-150 °C), screw speed (250-300 rpm) and feeder speed (15-30 rpm) on physical properties (expansion ratio, bulk density, hardness, crispiness) of extrudates were investigated and optimized using response surface methodology. Desirable crispy extrudates were obtained at higher screw speed 293 rpm, lower feeder speed 19 rpm, and medium to high temperature of 123 °C. Effect of extreme and intermediate process conditions on functional, proximate quality and colour of the extrudates were also evaluated.

High-Pressure Inactivation of Enzymes: A Review on Its Recent Applications on Fruit Purees and Juices.

In the last 2 decades high-pressure processing (HPP) has established itself as one of the most suitable nonthermal technologies applied to fruit products for the extension of shelf-life. Several oxidative and pectic enzymes are responsible for deterioration in color, flavor, and texture in fruit purees and juices (FP&J). The effect of HPP on the activities of polyphenoloxidase, peroxidase, ß-glucosidase, pectinmethylesterase, polygalacturonase, lipoxygenase, amylase, and hydroperoxide lyase specific to FP&J have been studied by several researchers. In most of the cases, partial inactivation of the target enzymes was possible under the experimental domain, although their pressure sensitivity largely depended on the origin and their microenvironmental condition. The variable sensitivity of different enzymes also reflects on their kinetics. Several empirical models have been established to describe the kinetics of an enzyme specific to a FP&J. The scientific literature in the last decade illustrating the effects of HPP on enzymes in FP&J, enzymatic action on those products, mechanism of enzyme inactivation during high pressure, their inactivation kinetics, and several intrinsic and extrinsic factors influencing the efficacy of HPP is critically reviewed in this article. In addition, process optimization of HPP targeting specific enzymes is of great interest from an industrial approach. This review will give a fair idea about the target enzymes specific to FP&J and the optimum conditions needed to achieve sufficient inactivation during HPP treatment.

Quantum-chemical (DFT, MP2) and spectroscopic studies (FT-IR and UV) of monomeric and dimeric structures of 2(3H)-Benzothiazolone.

Molecular geometry and vibrational wavenumbers of 2(3H)-Benzothiazolone (C7H5NSO, HBT) was investigated using density functional (DFT/B3LYP) method with 6-311+G(d,p) basis set. The vibrational wavenumbers are found to be in good agreement with experimental FT-IR spectra. Hydrogen-bonded dimer of HBT, optimized by counterpoise correction, was studied by MP2 and DFT/B3LYP at the 6-311+G(d,p) level and the effects of molecular association through NH---O hydrogen bonding were discussed. A detailed analysis of the nature of the hydrogen bonding, using topological parameters, such as electronic charge density, Laplacian, kinetic and potential energy density evaluated at bond critical points (BCP) has also been presented. The UV absorption spectra of the compound dissolved in ethanol and chloroform solutions were recorded in the range of 200-600 nm. The UV-vis spectrum of the title molecule was also calculated using TD-DFT method. The calculated energy and oscillator strength almost exactly reproduce the experimental data. Total and partial density of state (TDOS, PDOS) of the HBT in terms of HOMOs and LUMOs and molecular electrostatic potential (MEP) were calculated and analyzed. The electric dipole moment, polarizability and the first static hyper-polarizability values for HBT were calculated at the DFT/B3LYP with 6-311+G(d,p) basis set. The results also show that the HBT molecule may have nonlinear optical (NLO) comportment with non-zero values. Stability of the molecule arising from hyper-conjugative interactions and charge delocalization was analyzed using natural bond orbital (NBO) analysis.

Fermented milks and milk products as functional foods--a review.

Fermented foods and beverages possess various nutritional and therapeutic properties. Lactic acid bacteria (LAB) play a major role in determining the positive health effects of fermented milks and related products. The L. acidophilus and Bifidobacteria spp are known for their use in probiotic dairy foods. Cultured products sold with any claim of health benefits should meet the criteria of suggested minimum number of more than 106 cfu/g at the time of consumption. Yoghurt is redefined as a probiotic carrier food. Several food powders like yoghurt powder and curd (dahi) powder are manufactured taking into consideration the number of organisms surviving in the product after drying. Such foods, beverages and powders are highly acceptable to consumers because of their flavor and aroma and high nutritive value. Antitumor activity is associated with the cell wall of starter bacteria and so the activity remains even after drying. Other health benefits of fermented milks include prevention of gastrointestinal infections, reduction of serum cholesterol levels and antimutagenic activity. The fermented products are recommended for consumption by lactose intolerant individuals and patients suffering from atherosclerosis. The formulation of fermented dietetic preparations and special products is an expanding research area. The health benefits, the technology of production of fermented milks and the kinetics of lactic acid fermentation in dairy products are reviewed here.

Angiotensin-converting enzyme gene polymorphism in north Indian population with obstructive sleep apnea.

BACKGROUND: A deletion of 287-bp Alu repeat of angiotensin-converting enzyme (ACE) insertion/deletion (I/D) gene is associated with hypertension. PURPOSE: The aim of this study is to determine the frequency of ACE (I/D) polymorphism in patients with obstructive sleep apnea (OSA). METHODS: Genotyping of ACE (I/D) gene polymorphism and estimation of serum angiotensin-converting enzyme (SACE) activity were done in 813 subjects who underwent polysomnography. Of these, 395 were apneics and 418 were non-apneics. RESULTS: The frequencies of II genotype (OR = 1.8, 95 % CI 1.26-2.60, p = 0.001) and I allele (OR = 1.4, 95 % CI 1.13-1.69, p = 0.001) of ACE gene were found to be significantly increased in patients with OSA as compared to patients without OSA. Frequency of II genotype was significantly decreased (OR = 0.46, 95 % CI 0.28-0.77, p = 0.003) in OSA patients with hypertension. In contrast, the frequencies of ID (OR = 1.80, 95 % CI 1.08-2.99, p = 0.024) and DD genotypes (OR = 2.15, 95 % CI 1.30-3.57, p = 0.003) were significantly increased in this group. The activity of SACE was significantly decreased in the apneic group as compared to the non-apneic group (OR = 0.99, 95 % CI 0.98-1.00, p = 0.04). CONCLUSIONS: The findings suggest that II genotype confers susceptibility towards development of OSA whereas DD genotype confers susceptibility towards hypertension irrespective of OSA.

Isolated tuberculosis of the spleen: A case report and review of literature.

Isolated involvement of spleen in tuberculosis is a rare entity, particularly among immunocompetent hosts. Herein, we present a 28-year-old man with left abdominal discomfort for 2 years who was found to have a cystic lesion in spleen on evaluation. Eventually, he was diagnosed to have isolated splenic tuberculosis with an involvement of a single lymph node at the splenic hilum. In this rare form of tuberculosis, it seems that splenectomy in addition to standard antitubercular therapy is curative.

Microwave drying for safe storage and improved nutritional quality of green gram seed (Vigna radiata).

The present study describes the effect of the microwave-heating method on disinfestations and physico characteristics, viz., grain size, grain hardness, and nutritional quality, of the stored green gram seed. It has been observed that the use of the microwave-heating method not only prolongs the storage duration of the green gram seed but also enhances its nutritional quality. The effect of independent parameters, viz., microwave power level and time of exposure, on the moisture content, insect mortality, color, and antinutrient factor (phyic acid) was optimized using response surface methodology (RSM), with the optimized value for power of 808 W and time at 80 s. The optimally treated green gram seed has 8.9% moisture, 99.5% insect mortality, 2.22 Δa* (green color of seed), and 591.79 mg/100 g of antinutrient factor (phytic acid). The grain size (geometric mean diameter, D(m)) of the control (untreated) sample was 3.75 mm, and that of the microwave-treated sample using optimum conditions was 3.99 mm. The grain hardness of the control sample was 3.31 kg, and that of the microwave-treated sample using optimum conditions was 1.305 kg. In vitro protein digestibility (IVPD) of the control (untreated) sample was 83 ± 0.289%, and that of the microwave-treated sample using optimum conditions was 85 ± 0.296%. These values are significantly difference (p < 0.05). The mineral elements studied were Zn, Fe, Mg, Mn, Cu, K, Ca, and Na. The microwave treatment resulted in a non-significant (p < 0.05) effect for Mg, Mn, Cu, K, and Na but a significant (p < 0.05) effect for Zn, Ca, and Fe. The results indicate that the microwave heating not only increases the insect mortality but also reduces the moisture content and antinutritional factor (phytic acid), while the natural green color of the seed is not affected much. This study provides a novel and environmentally safe technique and increase in the nutritive quality.

Proton magnetic resonance spectroscopy of brain in obstructive sleep apnoea in north Indian Asian subjects.

BACKGROUND & OBJECTIVES: Repeated apnoeic/hypoapnoeic episodes during sleep may produce cerebral damage in patients with obstructive sleep apnoea (OSA). The aim of this study was to determine the absolute concentration of cerebral metabolites in apnoeic and non-apnoeic subjects from different regions of the brain to monitor the regional variation of cerebral metabolites. METHODS: Absolute concentration of cerebral metabolites was determined by using early morning proton magnetic resonance spectroscopy ((1)H MRS) in 18 apnoeic patients with OSA (apnoeics) having apnoea/hypopnoea index (AHI) >5/h, while 32 were non-apnoeic subjects with AHI< 5/h. RESULTS: The absolute concentration of tNAA [(N-acetylaspartate (NAA)+N-acetylaspartylglutamate (NAAG)] was observed to be statistically significantly lower (P<0.05) in apnoeics in the left temporal and left frontal gray regions compared to non-apnoeics. The Glx (glutamine, Gln + glutamate, Glu) resonance showed higher concentration (but not statistically significant) in the left temporal and left frontal regions of the brain in apnoeics compared to non-apnoeics. The absolute concentration of myo-inositol (mI) was significantly high (P<0.03) in apnoeics in the occipital region compared to non-apnoeics. INTERPRETATION & CONCLUSIONS: Reduction in the absolute concentration of tNAA in apnoeics is suggestive of neuronal damage, probably caused by repeated apnoeic episodes in these patients. NAA showed negative correlation with AHI in the left frontal region, while Cho and mI were positively correlated in the occipital region and Glx showed positive correlation in the left temporal region of the brain. Overall, our results demonstrate that the variation in metabolites concentrations is not uniform across various regions of the brain studied in patients with OSA. Further studies with a large cohort of patients to substantiate these observations are required.