Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “CAMPHOR”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,585 records · Page 88Linked to original sources
PubMed1992

Influence of endodontic materials on the bonding of composite resin to dentin.

We assessed the bond strength of a composite resin to dentin that had been in contact with different materials. Flat dentin surfaces in freshly extracted human teeth were covered for 15 min or 48 h with a 1-mm layer of a variety of materials. The products were mechanically removed and a composite resin cylindrical specimen bonded to the dentin surface using the Prisma universal bond system. After 7 days immersion at 37 degrees C in water, the tensile bond strength was tested. The results were compared with those on dentin surfaces not in contact with any endodontic material. Statistical analysis showed that some materials (Grossmans Cement, IRM, Maisto's slowly resorbable paste) reduced the strength of the bond or even precluded bonding. It is necessary to develop techniques that will eliminate this when restoring endodontically treated teeth.

Adhesiveness↗
PubMed1993

Influence of endodontic materials on the bonding of glass ionomer cement to dentin.

We assessed the bond strength of a glass ionomer cement to dentin that had been in contact with different materials. Flat dentin surfaces in freshly extracted human teeth were covered for 48 h with a 1 mm layer of a variety of materials that are used for temporary filling or root canal sealing. The products were mechanically removed and a glass ionomer cement cylindrical specimen bonded to the dentin surface. After 7-days immersion in 37 degrees C water the tensile bond strength was tested. The results were compared with those on dentin surfaces not in contact with any endodontic material. The statistical analysis showed that none of the materials used interfered with the bonding of the glass ionomer to dentin.

Analysis of Variance↗
PubMed1998

Directed evolution of new enzymes and pathways for environmental biocatalysis.

Biocatalysis is important in both natural and engineered environments. The major global reactions in the biospheric cycling of carbon, nitrogen, and other elements are catalyzed by microorganisms. The global carbon cycle includes millions of organic compounds that are made by plants, microorganisms, and organic chemists. Most of those compounds are transformed by microbial enzymes. Degradative metabolism is known as catabolism and yields principally carbon dioxide, methane, or biomass. Microbial catabolic enzymes are a great resource for biotechnology. They are the building blocks for engineering novel metabolic pathways and evolving improved enzymes in the laboratory. Two multicomponent bacterial oxygeneases, cytochrome P450cam and toluene dioxygenase, catalyze the dechlorination of polyhalogenated C2 compounds. Seven genes encoding those functional enzyme complexes were coexpressed in a Pseudomonas and shown to metabolize pentachloreothane to nonhalogenated organic acids that were metabolized further to carbon dioxide. In another example, the enzyme catalyzing the dechlorination of the herbicide atrazine was subjected to iterative DNA shuffling to produce mutations. By using a plate screening assay, mutated atrazine chlorohydrolase that catalyzed a more rapid dechlorination of atrazine was obtained. The mutant genes were sequences and found to encode up to 11 amino acid changes. Atrazine chlorohydrolase is currently being used in a model municipal water treatment system to test the feasibility of using enzymes for atrazine decontamination. These data suggest that the natural diversity of bacterial catabolic enzymes provides the starting point for improved biocatalytic systems that meet the needs of commercial applications.

Biodegradation, Environmental↗
PubMed1992

In vivo evaluation of photoprotection against chronic ultraviolet-A irradiation by a new sunscreen Mexoryl SX.

In a previous study on the hairless mouse it was shown that sub-erythemal doses of pure UV-A enhanced the numerous changes normally observed during chronological aging. A new sunscreen (a bis-benzylidene campho sulfonic acid derivative) has been synthesized in our research laboratory (lambda max: 345 nm, epsilon: 47,000). Its photoprotective properties against UV-A induced damages were assessed in our mouse model. Three month old albino hairless mice were exposed for 1 y to suberythemal doses (35 J/cm2) of UV-A obtained from a xenon source filtered through a WG 345 filter. One group of animals was exposed untreated, the other received a formulation containing 5% of the sunscreen prior to irradiation. At the end of the study the cutaneous properties of protected mice were compared to those of unprotected animals and to 3 and 15 month old unirradiated controls. We found that the visible changes induced by UV-A irradiation were mainly sagging and wrinkling. Histological and electron microscopic alterations consisted of hyperkeratosis, increased density of elastic fibers with alteration of fiber orientation and increased glycosaminoglycan deposits. Biochemical changes consisted of decreases in total collagen and collagen hydroxylation and increases in both collagen III/I + III ratio and fibronectin biosynthesis. All these changes were reduced or abolished by the sunscreen.

Animals↗
PubMed1994

Sunscreens with broad-spectrum absorption decrease the trans to cis photoisomerization of urocanic acid in the human stratum corneum after multiple UV light exposures.

The trans to cis photoisomerization of urocanic acid (UCA) in skin is considered to play an important role in the mechanism of immunosuppression. We have investigated the effects of skin type and various sunscreens with low sun protection factor (SPF) on the UV-induced cis-UCA formation in human skin after exposure to artificial UV light. The rate of cis-UCA formation depends little on the skin type and is reduced by topical application of sunscreens. The rate of cis-UCA formation decreases with increasing SPF and only broad-spectrum, highly protective sunscreens offer protection against the UV-induced formation of cis-UCA, which accumulates in the stratum corneum after multiple UV exposures. A theoretical approach to estimate the distribution of cis-UCA after irradiation indicates that this compound may diffuse into the deeper layers of the epidermis with D approximately 10(-17) m2/s, and that its elimination from the stratum corneum is mainly due to desquamation.

Camphanes↗
PubMed1996

Mexoryl SX protects against solar-simulated UVR-induced photocarcinogenesis in mice.

The aim of this study was to determine, for regulatory purposes, the potential of Mexoryl SX, a broad UVA absorber that also absorbs to some extent in the UVB, to modify the UV radiation (UVR)-induced murine skin tumor development and growth. Skh-hr1 mice were exposed to solar-simulated UVR 5 days per week for 40 weeks. Two control groups were irradiated without topical application, three groups received a sunscreen preparation containing either the UVA absorber, Mexoryl SX at 5 or 10% concentration, or a filter that absorbs principally in the UVB, 2-ethylhexyl-p-methoxycinnamate (2-EHMC) at 5% concentration, introduced as a comparator test article. Sunscreen application was performed before UVR exposure 3 days per week and after UVR exposure on the other 2 days (consistent with the design of a standard photocarcinogenesis safety test). Two different weekly UVR doses were administrated: the lower dose was given to one group of unprotected animals, whereas the higher dose was administrated to the other unprotected group and to the three sunscreen-treated groups. The two UVR control groups demonstrated a UVR-dependent response for cumulative tumor prevalence, tumor yield and median latent period. Neither concentration of Mexoryl SX increased the probability of tumor development; consistent with the principles for safety testing, this provides evidence in that it is safe for use in sunlight. Although this study was explicitly designed as a safety test, the results also provide some clues about the efficacy of Mexoryl SX in decreasing the probability of tumor development. Topical administration of Mexoryl SX, at both concentrations, resulted in a 6 week delay in the median latent period compared to high UVR controls, whereas 5% 2-EHMC delayed the median latent periods only by 2 weeks. Tumor prevalence and yield show the same efficacy differences between the two sunscreen ingredients. Tumor protection factors were calculated from these results and found to be equal to 2.4 for the two preparations containing Mexoryl SX and to 1.3 for the 5% 2-EHMC preparation. These findings illustrate the efficacy of Mexoryl SX in preventing UVR-induced carcinogenesis.

Animals↗
PubMed1978

Endodontics.

Explore the source record for details and available documents.

Anti-Infective Agents↗
PubMed1984

Respiratory rhythm generation in the in vitro brain stem-spinal cord preparation of the neonatal rat.

An in vitro preparation was described for studying electrical activity of mammalian brain stem and spinal cord. The brain stem and the spinal cord were isolated from 0-4-day-old rats, placed in a bath and perfused with modified Krebs solution. Various reflex responses could be recorded from cranial nerves by stimulation of other cranial nerves. The preparation was viable for more than 7 h. Spontaneous periodic neural activity could be recorded from phrenic, hypoglossal and other spinal nerves. The periodic discharges of phrenic nerves are synchronized with those of ventral roots C4 and the upward movements of the thorax which was isolated together with the spinal cord. The rhythm of periodic activity seems to be generated in the brain stem. The periodic activity was enhanced by perfusion with low pH solution and depressed by high pH solution. It was markedly depressed by opioid compounds such as enkephalin. It is suggested that this periodic activity corresponds to the respiratory rhythm generated in the brain stem of intact animals. The present preparation may be valuable for elucidating cellular mechanisms of generation and control of respiratory rhythm in the mammalian central nervous system.

Animals↗
PubMed2005

Anti-AIDS agents 65: investigation of the in vitro oxidative metabolism of 3',4'-Di-O-(-)-camphanoyl-(+)-cis-khellactone derivatives as potent anti-hiv agents.

3',4'-Di-O-(-)-camphanoyl-(+)-cis-khellactone (DCK) is a synthetic khellactone ester that exhibits potent in vitro anti-human immunodeficiency virus (HIV) activity with a mechanism distinct from clinically used anti-HIV agents. Several series of mono- and di-substituted DCK derivatives (DCKs) have previously been synthesized, and their structure-activity relationships are well established. To optimize DCK as a drug lead and to guide further structural modifications, metabolic stabilities and metabolite structures were analyzed. In vitro metabolic stabilities of DCKs in human liver microsomes were assessed using high performance liquid chromatography (HPLC) with UV detection to establish structure-metabolism relationships (SMRs). HPLC coupled with ion trap mass spectrometry was used to identify the metabolite structures. The results indicated that DCKs undergo rapid oxidation on the lipophilic camphanoyl moieties and the substituents on the khellactone do not alter the rate or the metabolic pathways for this compound type. Our SMR and metabolite analysis study suggested that the two camphanoyl ester moieties are the determinants of the low metabolic stability and that structural alteration in the two esters may be necessary to improve metabolic profiles of DCKs.

Anti-HIV Agents↗
PubMed1998

Activation by diverse xenochemicals of the 51-base pair phenobarbital-responsive enhancer module in the CYP2B10 gene.

By extending previous studies of the phenobarbital (PB)-responsive 132-base pair (bp) enhancer sequence in the CYP2B10 gene, we have delimited a 51-bp enhancer element that is fully inducible by PB in mouse primary hepatocytes. Sixteen structurally unrelated phenobarbital-type inducers activated the 51-bp enhancer element in transient transfection assays. The results thus indicate that most PB-type inducers, if not all inducers, increase the transcription of the CYP2B10 gene by activating this 51-bp element, now designated PB-responsive enhancer module or PBREM.

Animals↗
PubMed1992

Laser-enhanced NMR spectroscopy.

Experimental studies show that optical irradiation far from any absorption bands can shift the resonances in a nuclear magnetic resonance (NMR) spectrum without significant heating. This effect may lead to increased dispersion in NMR studies of complex molecules.

Camphor↗