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1.
J Biotechnol ; 254: 1-8, 2017 Jul 20.
Article in English | MEDLINE | ID: mdl-28602792

ABSTRACT

In the present study, we compared the effects of Al3+ ions and alumina (Al2O3) nanoparticles (NPs) on growth and biochemical parameters of cabbage seedlings. The seedlings were treated with A=698.8µM Al3+ions and A1=101.8µM, A2=253.8µM, A3=507.7µM, A4=1.02mM, A5=2.17mM NPs of Al2O3 in 700mL Hoagland solution. The untreated seedlings were taken as control. It was observed that aluminium ions were phytotoxic and adversely affected seedling growth and biochemical parameters of the test crop with stunting of the stem growth, while lower doses of alumina NPs enhanced seedling growth, pigments, sugar and protein contents of cabbage (Brassica oleracea var. capitata) seedlings. Higher doses of alumina NPs adversely affected biochemical parameters and nitrate reductase activities of the treated seedlings. Alumina NPs induced activities of antioxidant enzymes viz. SOD, CAT and POX. Antioxidant enzyme activities increased under all treatments with maximum increase in the seedlings treated with aluminium ions and higher concentrations of alumina NPs. The lower amount of alumina NPs buttressed the metabolic processes of the test crop and appeared to mitigate the phytotoxic effects of aluminium ions.


Subject(s)
Antioxidants/pharmacology , Brassica/growth & development , Metal Nanoparticles/chemistry , Seedlings/growth & development , Aluminum Oxide/chemistry , Aluminum Oxide/pharmacology , Antioxidants/chemistry , Brassica/drug effects , Brassica/metabolism , Catalase/metabolism , Ions/pharmacology , Seedlings/drug effects , Seedlings/metabolism , Superoxide Dismutase/metabolism
2.
Front Microbiol ; 8: 330, 2017.
Article in English | MEDLINE | ID: mdl-28316594

ABSTRACT

Plasmonic nanoparticles (NPs) such as silver and gold have fascinating optical properties due to their enhanced optical sensitivity at a wavelength corresponding to their surface plasmon resonance (SPR) absorption. Present work deals with the fabrication of silver nanoparticles decorated cotton (SNDC) fibers as a cheap and efficient point of contact disinfectant. SNDC fibers were fabricated by a simple microwave assisted route. The microwave power and irradiation time were controlled to optimize size and density of silver nanoparticles (SNPs) on textile fibers. As prepared cotton fabric was characterized for ATR-FTIR, UV-VIS diffuse reflectance, SEM and TEM investigations. Size of SNPs as well as total density of silver atoms on fabric gets increased with the increase of microwave power from 100 W to 600 W. The antibacterial efficacy of SNPs extracted from SNDC fibers was found to be more effective against Gram-negative bacteria than Gram-positive bacteria with MIC 38.5 ± 0.93 µg/mL against Salmonella typhimurium MTCC-98 and 125 ± 2.12 µg/mL against Staphylococcus aureus MTCC-737, a linear correlation coefficient with R2 ranging from ∼0.928-0.935 was also observed. About >50% death cells were observed through Propidium Iodide (PI) internalization after treatment of SNPs extracted from SNDC fibers with concentration 31.25 µg/mL. Generation of ROS and free radical has also been observed which leads to cell death. Excellent Escherichia coli deactivation efficacy suggested that SNDC fibers could be used as potentially safe disinfectants for cleaning of medical equipment, hand, wound, water and preservation of food and beverages.

3.
J Biotechnol ; 233: 84-94, 2016 Sep 10.
Article in English | MEDLINE | ID: mdl-27422354

ABSTRACT

In the present study, zinc oxide nanoparticles (ZnO NPs) were rapidly synthesized at room temperature by treating zinc acetate dihydrate with the flower extract of Elaeagnus angustifolia (Russian olive). The formation of ZnO NPs was primarily confirmed by UV-visible absorption spectrum in the range of 250-700nm. XRD analysis and DLS particle size analyzer revealed the size of ZnO NPs. The FTIR spectrum revealed the presence of phytochemicals in the flower extract mediated ZnO NPs. Moreover, the morphology of the ZnO NPs was determined using SEM. Seeds of Solanum lycopersicum (tomato) were separately treated with different concentrations of synthesized ZnO NPs and zinc sulphate (ZnSO4) salt suspensions (common zinc supplement). The effect of these treatments on seed germination, seedling vigor, chlorophyll, protein and sugar contents as well as on the activities of lipid peroxidation and antioxidant enzyme were studied. Leaves of plants treated with 6.1mM concentration of ZnO NPs recorded maximum reflectance while it was minimum in plants treated with 1.2mM concentration of NPs. The effect of synthesized ZnO NPs on seedling vigor, pigment, protein and sugar content was found affirmative at lower concentrations contrary to control and ZnSO4 salt. The inhibitory effect at higher concentration of NPs indicated importance in the precise application of NPs, in Zn deficient system, where plant response varies with concentration. To the best of our knowledge this is the first report on Elaeagnus angustifolia mediated synthesis of ZnO NPs and their effects on germination and physiological activity of tomato.


Subject(s)
Germination/drug effects , Metal Nanoparticles/chemistry , Plant Extracts/chemistry , Solanum lycopersicum/drug effects , Zinc Oxide/chemistry , Elaeagnaceae/chemistry , Flowers/chemistry , Green Chemistry Technology , Solanum lycopersicum/metabolism , Metal Nanoparticles/toxicity , Plant Leaves/chemistry , Seeds/drug effects , Zinc Oxide/metabolism
4.
Biotechnol Lett ; 38(4): 545-60, 2016 Apr.
Article in English | MEDLINE | ID: mdl-26721237

ABSTRACT

Nanotechnology is a new and emerging technology with wealth of applications. It involves the synthesis and application of materials having one of the dimensions in the range of 1-100 nm. A wide variety of physico-chemical approaches are being used these days for the synthesis of nanoparticles (NPs). However, biogenic reduction of metal precursors to produce corresponding NPs is eco-friendly, less expensive, free of chemical contaminants for medical and biological applications where purity of NPs is of major concern. Biogenic reduction is a "Bottom Up" approach similar to chemical reduction where a reducing agent is replaced by extract of a natural products with inherent stabilizing, growth terminating and capping properties. Furthermore, the nature of biological entities in different concentrations in combination with reducing organic agents influence the size and shape of NPs. Present review focuses on microbes or plants based green synthesis of Ag, Au, Cu, Fe, Pd, Ru, PbS, CdS, CuO, CeO2, Fe3O4, TiO2, and ZnO NPs and their potential applications.


Subject(s)
Green Chemistry Technology/methods , Metal Nanoparticles/chemistry , Nanotechnology/methods , Plant Extracts/chemistry , Semiconductors
5.
Food Chem Toxicol ; 53: 160-7, 2013 Mar.
Article in English | MEDLINE | ID: mdl-23220615

ABSTRACT

The study explores the efficacy of Cinnamomum glaucescens essential oil (EO) as insecticidal, antifungal, antiaflatoxin and antioxidant agent so as to recommend its application as plant based preservatives for food commodities. The study reports the chemical characterization of C. glaucescens oil and its 100% insecticidal activity against insect pest Callosobruchus chinensis on 12 h exposure and 98.74% oviposition deterrency at 0.15 µl/ml. The EO significantly inhibited growth and aflatoxin production by toxigenic strain of Aspergillus flavus LHP-10 at 4.5 and 3.5 µl/ml respectively. EO also showed appreciable antioxidant activity (IC(50) value=15.1 µl/ml), non phytotoxic nature on chickpea seed germination and in vivo potential as fumigant in food system providing 71.07% protection of chickpea samples from fungal contamination and 100% antifeedant activity against the insect invasion. The EO exhibited non-mammalian toxicity showing high LD(50) (3971.34 µl/kg) during oral toxicity on mice.


Subject(s)
Antifungal Agents/pharmacology , Antioxidants/pharmacology , Cinnamomum/chemistry , Fungi/drug effects , Insecta/drug effects , Oils, Volatile/pharmacology , Aflatoxins/antagonists & inhibitors , Aflatoxins/biosynthesis , Animals , Aspergillus flavus/drug effects , Cicer/drug effects , Cicer/microbiology , Female , Food Contamination/prevention & control , Food Microbiology , Food Storage , Inhibitory Concentration 50 , Lethal Dose 50 , Male , Mice
6.
Eur J Clin Microbiol Infect Dis ; 31(12): 3375-83, 2012 Dec.
Article in English | MEDLINE | ID: mdl-22865029

ABSTRACT

The purpose of this investigation was to try to understand the antibacterial mechanism of L-(-)-usnic acid isolated for the first time from fruticose lichen Usnea subfloridana using clinical isolates of methicillin-resistant Staphylococcus aureus (MRSA). The minimum inhibitory concentration (MIC) of L-(-)-usnic acid against the clinical isolates of MRSA and reference strain S. aureus MTCC-96 (SA-96) was in the range 25-50 µg/ml. Treatment of both reference and clinical strains (MRSA-ST 2071) with four-fold MIC concentrations (100-200 µg/ml) of L-(-)-usnic acid reduced the viability of cells without damaging the cell wall. However, the loss of 260 nm absorbing material and increase in propidium iodide uptake was observed in both of the strains. Similarly, a combined effect of L-(-)-usnic acid (25-50 µg/ml) and 7.5 % NaCl resulted in a reduced number of viable cells within 24 h in comparison to the control. These observations clearly indicate that L-(-)-usnic acid exerts its action by disruption of the bacterial membrane. Further, in vivo efficacy showed that L-(-)-usnic acid significantly (p < 0.001) lowered the microbial load of spleen at doses ranging from 1 to 5 mg/kg. Further, toxicity studies in infected mice at doses 20 times higher than the efficacious dose indicated L-(-)usnic acid to be safe. Paradoxically, L-(-)usnic acid exhibited changes in serum triglycerides, alkaline phosphatase (ALKP) and liver organ weight in the healthy mice administered with only 25 mg/kg body weight. The results obtained in this study showed that natural L-(-)-usnic acid exerts its antibacterial activity against MRSA by disruption of the cell membrane. Further, the natural L-(-)-usnic acid was found to be safe up to 100 mg/kg body weight, thereby, making it a probable candidate for treating S. aureus infections.


Subject(s)
Anti-Bacterial Agents/pharmacology , Benzofurans/pharmacology , Cell Membrane/drug effects , Methicillin-Resistant Staphylococcus aureus/drug effects , Animals , Anti-Bacterial Agents/adverse effects , Anti-Bacterial Agents/isolation & purification , Anti-Bacterial Agents/therapeutic use , Benzofurans/adverse effects , Benzofurans/isolation & purification , Benzofurans/therapeutic use , Colony Count, Microbial , Disease Models, Animal , Female , Humans , Methicillin-Resistant Staphylococcus aureus/isolation & purification , Mice , Microbial Sensitivity Tests , Microbial Viability/drug effects , Spleen/microbiology , Staphylococcal Infections/drug therapy , Staphylococcal Infections/microbiology , Usnea/chemistry
7.
Nat Prod Res ; 26(20): 1945-7, 2012.
Article in English | MEDLINE | ID: mdl-22007903

ABSTRACT

The essential oil of Melaleuca decora twigs has been obtained by hydrodistillation and analysed by GC-FID, GC/MS and (1)H-, (13)C-NMR experiments. The most abundant class of compounds in M. decora twig oil was phenylpropanoids represented by methyl eugenol (92.4%) as the most exclusive constituent. In terms of molecular diversity, phenylpropanoids dominate M. decora essential oil with low terpenoid (3.9%) proportion.


Subject(s)
Melaleuca/chemistry , Oils, Volatile/chemistry , Chromatography, Gas , Gas Chromatography-Mass Spectrometry , Magnetic Resonance Spectroscopy
8.
J Assoc Physicians India ; 59: 552-6, 2011 Sep.
Article in English | MEDLINE | ID: mdl-22334967

ABSTRACT

OBJECTIVES: The present study was designed to assess hepatic and renal dysfunction in Plasmodium falciparum malaria, and evaluate if such abnormalities had any bearing with the hemorrheological dysfunction. METHODS: Sixty consecutive patients of Plasmodium falciparum malaria with hepatic and renal dysfunction (Group A) and twenty consecutive cases of uncomplicated falciparum malaria (Group B) were studied. Patients with past history of alcoholism, jaundice, chronic renal failure, bleeding diathesis or coagulopathy were excluded from the study. Laboratory investigations done were liver and renal function tests, complete blood count and coagulation profile. The data collected was analysed to inter - correlate parameters of hepatic, renal and hemorrheological dysfunction. RESULTS: In Group A, all had rigor and chill, icterus while 57% had oliguria and hepatomegaly, 37% splenomegaly, with less than 2% having overt bleeding diathesis. On evaluation, in Group A, 57% had acute renal failure, mean value of bilirubin was 13.91 (+/- 12.53) mg/dL, ALT 76.92 (+/- 37.48) IU/ml, AST 135.32 (+/- 97.33) IU/ml, mean PT was 13.03 (+/- 2.22) seconds, mean aPTT was 31.69 +/- 6.76 seconds, FDP by D-dimer was raised in 53% and LDH was raised in 78% respectively. In Group B mean PT was 11.93 (+/- 1.51) seconds, mean APTT was 29.39 +/- 2.89 seconds and FDP by D-dimer was raised in 30% respectively. Thrombocytopenia was seen in 26% cases in Group A and 15% cases in Group B. On analysis, in Group B, there was statistically significant negative correlation of total platelet count with serum AST (p = .010) and serum ALT (p = .036), serum ALP with BT (p = .036), but positively with CT (p = .006) and aPTT (p = .036). In Group A, serum bilirubin was found to have significant negative correlation with haemoglobin (p = .019),positive correlation with aPTT (p = .037), urea (p = .000) and serum creatinine (p = .000), serum ALP Positively with serum urea (p = .025) and serum creatinine (p = .037), serum urea negatively with haemoglobin(p = .015), so also did serum creatinine (p = .025),prothrombin time positively with serum urea(p = 0.037) and serum creatinine (p = 0.013), serum FDP positively with serum urea (p = 0.038) and serum creatinine (p = 0.022), bleeding time positively with serum AST(p = .002). CONCLUSION: Despite less than 2% of patients in Group A having clinically overt bleeding diathesis, raised FDP (53%), prolonged aPTT (67%), low total platelet count (26%) and anemia (87%) were found in a significant number of patients, suggesting subclinical DIC. Therefore patients with Plasmodium falciparum malaria have high incidence of subclinical haemorrheological disorders which do not amount to overt DIC but adversely affect renal function contributing to acute renal failure.


Subject(s)
Jaundice/etiology , Malaria, Falciparum/complications , Renal Insufficiency/etiology , Adolescent , Adult , Aged , Aspartate Aminotransferases/blood , Bilirubin/blood , Female , Fibrin Fibrinogen Degradation Products , Hemoglobins/analysis , Humans , Male , Middle Aged , Partial Thromboplastin Time , Platelet Count , Thrombocytopenia/complications , Young Adult
9.
Genet Mol Res ; 9(3): 1535-44, 2010 Aug 10.
Article in English | MEDLINE | ID: mdl-20714995

ABSTRACT

The genus Swertia is well known for its medicinal properties, as described in the Indian pharmacopoeia. Different members of this genus, although somewhat similar in morphology, differ widely in their pharmacological and therapeutic properties. The most important species of this genus, with maximal therapeutic properties, is S. chirayita, which is often adulterated with other less-potent Swertia spp. There is an existing demand in the herbal drug industry for an authentication system for Swertia spp, in order to enable their commercial use as genuine phytoceuticals. To this end, we used amplified fragment length polymorphism (AFLP) to produce DNA fingerprints for six Swertia species. Nineteen accessions (2 of S. chirayita, 3 of S. angustifolia, 2 of S. bimaculata, 5 of S. ciliata, 5 of S. cordata, and 2 of S. alata) were used in the study, which employed 64 AFLP selective primer pairs. Only 46 selective primer pairs were found to be useful for all the accessions. A total of 5312 fragments were produced by these 46 primer pairs. Species-specific markers were identified for all six Swertia species (131 for S. chirayita, 19 for S. angustifolia, 181 for S. bimaculata, 47 for S. ciliata, 94 for S. cordata, and 272 for S. alata). These AFLP fingerprints of the Swertia species could be used to authenticate drugs made with Swertia spp and to resolve adulteration-related problems faced by the commercial users of these herbs.


Subject(s)
Amplified Fragment Length Polymorphism Analysis/methods , Swertia/genetics , DNA Fingerprinting , Phylogeny , Swertia/classification
10.
J Nanosci Nanotechnol ; 9(9): 5367-71, 2009 Sep.
Article in English | MEDLINE | ID: mdl-19928229

ABSTRACT

Synthesis of colloidal solution of TiO2 Nanoparticles by pulsed laser ablation in water, without any surfactant is studied. Fundamental wavelength of Nd:YAG laser operating at 35 mJ/pulse energy, 10 ns pulse width and 10 Hz repetition rate is used for the ablation of titanium target placed in water. Laser ablation of Titanium target in the water produces violet colored, highly stable colloidal solution for months even in the absence of any capping agents. UV-Visible absorption, Photoluminescence, X-ray diffraction, SEM and FTIR spectroscopic technique are used for the characterization of produced Nanomaterials. Six emission bands are observed in the photoluminescence spectrum of the produced sample. Origin of all the lines in the PL spectrum has been discussed. Possible reaction mechanism for the laser matter interaction and synthesis of nanomaterial are discussed.

11.
J Assoc Physicians India ; 57: 657-9, 2009 Sep.
Article in English | MEDLINE | ID: mdl-20214007

ABSTRACT

Paget's disease of bone is a rare disorder in India. Patients are usually asymptomatic and incidental radiological investigation invariably clinches the diagnosis. Increased alkaline phosphatase, X-ray, CT scan and scintiscan of bone can be done to confirm the diagnosis. Here we report a case of an 85-yr-old lady who had bilateral hearing loss for last 10 yrs, was admitted incidentally for some other complaints and on investigation diagnosed to have advanced Paget's disease of bone.


Subject(s)
Osteitis Deformans/diagnostic imaging , Aged, 80 and over , Brain/diagnostic imaging , Female , Humans , Skull/diagnostic imaging , Tomography, X-Ray Computed
12.
Nature ; 442(7100): 287-90, 2006 Jul 20.
Article in English | MEDLINE | ID: mdl-16855587

ABSTRACT

The determination of melt distribution in the crust and the nature of the crust-mantle boundary (the 'Moho') is fundamental to the understanding of crustal accretion processes at oceanic spreading centres. Upper-crustal magma chambers have been imaged beneath fast- and intermediate-spreading centres but it has been difficult to image structures beneath these magma sills. Using three-dimensional seismic reflection images, here we report the presence of Moho reflections beneath a crustal magma chamber at the 9 degrees 03' N overlapping spreading centre, East Pacific Rise. Our observations highlight the formation of the Moho at zero-aged crust. Over a distance of less than 7 km along the ridge crest, a rapid increase in two-way travel time of seismic waves between the magma chamber and Moho reflections is observed, which we suggest is due to a melt anomaly in the lower crust. The amplitude versus offset variation of reflections from the magma chamber shows a coincident region of higher melt fraction overlying this anomalous region, supporting the conclusion of additional melt at depth.

13.
J Pharm Biomed Anal ; 28(3-4): 447-52, 2002 May 15.
Article in English | MEDLINE | ID: mdl-12008123

ABSTRACT

A rapid sensitive and reproductive reversed phase high performance liquid chromatographic method with photo diode arrray detection is described for the simultaneous quantification of major oleane derivatives: arjunic acid (4), arjunolic acid (3), arjungenin (2) and arjunetin (1) in Terminalia arjuna extract. The method involves the use of a Waters Spherisorb S10 ODS2 column (250 x 4.6 mm, I.D., 10 microm) and binary gradient mobile phase profile. The various other aspects of analysis viz. Extraction efficiency, peak purity and similarity were validated using a photo diode array detector.


Subject(s)
Plants, Medicinal/chemistry , Calibration , Chromatography, High Pressure Liquid , India , Oleanolic Acid/analogs & derivatives , Oleanolic Acid/analysis , Plant Epidermis/chemistry , Reproducibility of Results , Solvents
14.
Med J Armed Forces India ; 58(4): 310-4, 2002 Oct.
Article in English | MEDLINE | ID: mdl-27407421

ABSTRACT

A pilot cross-sectional study among 262 service sportsmen belonging to different sports disciplines was carried out to evaluate various indicators of muscle strength, such as peak torque, peak torque to weight, time to peak torque, maximum power, explosive work etc., using isokinetic testing during flexion and extension of the knee joint in sitting positions at different angles. It was found that peak torque varied significantly among the various sports disciplines depending on the requirement of each sports discipline (p < 0.01). The relevance, advantages and limitations of the tests to enhance sports performance have been discussed. However, discussion has been restricted to review of western literature on the subject as no Indian studies in the field were available for comparison.

15.
Planta Med ; 67(6): 575-7, 2001 Aug.
Article in English | MEDLINE | ID: mdl-11509988

ABSTRACT

Besides shikonin and arnebifuranone, two new shikonin esters isolated from the roots of Arnebia hispidissima have been characterized as butylshikonin and 2'-methyl-hexa-1',3'-dienoylshikonin by physicochemical methods. Arnebifuranone is the first report from this species.


Subject(s)
Magnoliopsida/chemistry , Naphthoquinones/isolation & purification , Food Coloring Agents/chemistry , Naphthoquinones/chemistry , Plant Extracts/chemistry , Plant Roots/chemistry
16.
Med J Armed Forces India ; 56(1): 24-26, 2000 Jan.
Article in English | MEDLINE | ID: mdl-28790638

ABSTRACT

A study was carried out to find out the effects of prior physical activity, sports participation and prior military training on the incidence of stress fractures among Gentlemen Cadets (GC's) undergoing military training at Indian Military Academy (IMA). One thousand and fourteen GC's were followed up for a period of 12 weeks. Thirty-seven GC's developed stress fractures during the study period. The incidence of stress fractures was significantly higher in GC's without any prior military training (p=0.0009). They were compared with 100 healthy controls drawn from the study population to study the influence of the other mentioned factors. There was no significant association between prior physical activity and stress fractures (OR=0.74, 95% CL=0.26 to 2.05, p=0.688). There was also no significant relationship between sports participation and stress fractures (OR=0.79. 95% CCL=0.35 to 1.81, p=0.684).

17.
Phytother Res ; 13(3): 239-41, 1999 May.
Article in English | MEDLINE | ID: mdl-10353168

ABSTRACT

An improved extraction procedure resulted into a six-fold yield of bioactive fraction than the usual extraction method with a high per cent of feeding deterrence against 3rd instar larvae of Spilarctia obliqua and Spodoptera litura. The effective concentration (EC50) of PH-2 was 4321 and 4155 ppm against the two insects. No loss in feeding deterrency was recorded when the bioactive ether fraction, PH-2 was exposed to sunlight for 6 h.


Subject(s)
Feeding Behavior/drug effects , Insecta/drug effects , Plant Extracts/pharmacology , Polygonaceae/chemistry , Animals , Insecta/embryology , Insecta/physiology , Larva/drug effects , Plant Extracts/chemistry , Sunlight
18.
J Ethnopharmacol ; 64(1): 69-77, 1999 Jan.
Article in English | MEDLINE | ID: mdl-10075124

ABSTRACT

In a survey at Lucknow, India, the seedlings of plant species which are prescribed in the Indian traditional system of medicine for a variety of infectious diseases were found to predominate on fresh or decomposing cattle dung, a harsh medium for plant growth due to high microbial load and other abiotic factors. Plants of most of the common species did not occur on the cattle dung heaps. It was hypothesized that plant species which are able to grow on cattle dung may have antimicrobial compounds in their seeds to protect them from microbial attack. In confirmation, the seeds of 15 of the coprophilous (kopros--dung, philein--to love) plant species, identified as occurring most frequently on fresh/decomposing cattle dung were directly tested against eight bacterial and three fungal strains. Interestingly, seeds of all the examined species exhibited antimicrobial activity. The seeds of the species found more frequently on the cattle dung heaps possessed higher levels of antimicrobial activities.


Subject(s)
Anti-Bacterial Agents/isolation & purification , Antifungal Agents/isolation & purification , Medicine, Traditional , Plants, Medicinal , Seeds , Animals , Cattle , Feces/microbiology , India , Plants, Medicinal/chemistry , Seeds/chemistry
19.
Science ; 260(5105): 204-7, 1993 Apr 09.
Article in English | MEDLINE | ID: mdl-17807182

ABSTRACT

Seismic reflection profiles across many continental margins have imaged bottom-simulating reflectors (BSRs) parallel to the seabed; these are often interpreted as the base of a zone in which methane hydrate "ice" is stable. Waveform inversion of seismic reflection data can be used to estimate from seismic data worldwide the velocity structure of a BSR and its thickness. A test of this method at a drill site of the Ocean Drilling Program predicts that sediment pores beneath the BSR contain free methane for approximately 30 meters. The hydrate and underlying gas represent a large global reservoir of methane, which may have economic importance and may influence global climate.

20.
J Neurol Sci ; 49(3): 353-61, 1981 Mar.
Article in English | MEDLINE | ID: mdl-7217988

ABSTRACT

In rats anesthetized with ethanol 4.0 g/kg i.p. the dura overlying the parietal cortex was exposed and superfused with 100% ethanol for 1 h. After 6 days survival the underlying cortex was stained with a silver method that is selective for degenerating axons and their terminals. No degeneration was found in the superfused cortex, although heat-lesioned tissue stained concurrently showed axonal degeneration and so validated the technique. Electron microscopy after 3-20 days survival did not show any degeneration, and synapses of normal appearance were present immediately beneath the cortical surface. In other rats the ethanol concentration in the superfused tissue was assayed in 0.4 mm thick discs sectioned with a vibratome from a 4-mm diameter core cut with a trocar from the cortex immediately after 1 h of superfusion. The ethanol was eluted in 2% TCA, and an aliquot assayed enzymatically. A second elution of the tissue disc contributed a further 5% of the ethanol content indicating a partition coefficient for ethanol between wet brain tissue and 2% TCA of about 10. The total concentration of ethanol in the superficial cortex was found to be about 0.82 M or 3.8%. This estimation was confirmed by superfusion with 14C-labelled ethanol and scintillation counting. Thus neurons in the cerebral cortex did not degenerate after exposure for 1 h to a concentration of ethanol that was 3 times greater than the concentration that causes death in a rat by paralysis of the respiratory centre (1.2%).


Subject(s)
Cerebral Cortex/drug effects , Ethanol/adverse effects , Administration, Topical , Animals , Axons/drug effects , Axons/ultrastructure , Cerebral Cortex/metabolism , Dose-Response Relationship, Drug , Ethanol/metabolism , Male , Neurons/drug effects , Rats
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