Biomedical subjects

H G Edwards

Publications and source records attributed to H G Edwards.

At least 19 recordsLinked to original sources

PubMed2001

Application of FT-Raman spectroscopy to the characterisation of parchment and vellum, I; novel information for paleographic and historiated manuscript studies.

Raman spectra of parchment and vellum have been recorded and used to characterise materials used in mediaeval (10th century) and later works. These studies support our work on the characterisation of pigments used in historiated manuscripts and provide the basis for future studies of the interaction between pigments, binders and parchment or vellum. Examination of the undecorated parts of the manuscripts or books has been undertaken to ascertain if there are traces remaining of the procedures used to prepare the materials; in several cases, there is spectroscopic evidence for the presence of sulphates and slaked lime, which were used in the preparations of vellums for scriptoria. In one 14th century cantoral, there is evidence for paper being used as backing on the verso side of the vellum, probably from an early repair.

Animals↗

PubMed2001

A study of amber and copal samples using FT-Raman spectroscopy.

FT-Raman spectra were collected from fossil resins originating from a variety of geographical locations. The spectral profiles of most of the fossil resins could be related to modern resins containing diterpenoid components with predominantly labdane skeletons. The spectra collected from the fossil resin sample from Borneo differed from other fossil resins and was found to contain triterpenoid components. The differences in the spectral profile of fossil resins containing diterpenoid components are shown to relate to differences in level of maturation rather than geographical origin. FT-Raman spectra of fossil resins cannot be used to distinguish source although the degree of maturation can be used as an indicator to narrow the range of possible geographical origins.

Amber↗

PubMed2001

Mediaeval cantorals in the Valladolid Biblioteca: FT-Raman spectroscopic study.

Raman spectroscopic studies of three mediaeval cantorals in the Biblioteca of the University of Valladolid has revealed information about the pigments used on these large manuscripts. Although executed in a simple colour palette, very pure cinnabar was used as the major colourant, offsetting the carbon black of the verses and script. A dark blue colour was achieved using a mixture of azurite (basic copper carbonate) and carbon, whereas a light blue colour was azurite alone. A grey colour was achieved using azurite, carbon particles and a calcareous 'limewash'. A yellow pigment, used sparely in the cantorals was ascribed to saffron; unusually, there was no evidence for the presence of the yellow mineral pigments orpiment, realgar and massicot. In several regions of the vellum specimens, evidence for biodeterioration was observed through the signatures of hydrated calcium oxalate. We report for the first time the Raman spectra of pigment in situ on a vellum fragment, which also shows evidence of substrate bands; comparison of black and red pigmented regions of vellum specimens has shown the presence of calcium oxalate in the black pigmented script but not in the red pigment regions, which suggests that the cinnabar in the red-pigmented regions acts as a toxic protectant for the vellum substrate against biological colonisation processes.

Journal Article↗

PubMed2000

Vibrational raman spectroscopic study of scytonemin, the UV-protective cyanobacterial pigment.

The Raman spectrum of the photoprotective pigment scytonemin found in cyanobacterial sheaths has been obtained for the first time. Its skeletal structure is extensively conjugated and unique in nature. Detailed molecular vibrational assignments are proposed and a distinctive group of four corroborative vibrational bands have been identified as unique indicators for the compound. These bands, especially a prominent feature at wavenumber 1590 cm(-1), are sufficiently conspicuous to be detectable in the mixed biomolecular pools of undisturbed natural microbial communities. This has been confirmed by demonstrating the Raman spectral bands for scytonemin in a sample of an intact intertidal cyanobacterial mat.

Cyanobacteria↗

PubMed1999

Lichen biodeterioration of the Convento de la Peregrina, Sahagún, Spain.

Lichen encrustations from Diploschistes scruposus involved in the biodeterioration of the 13th Century Convento de la Peregrina in Sahagún Spain, have been analyzed using Raman spectroscopy. The vibrational spectra are characteristic of calcium oxalate monohydrate, beta-carotene, chlorophyll, and para-depside phenolic acids such as atranorin, lecanoric acid, and diploschistesic acid. The destructive colonization of the monumental stonework is highlighted and evidence presented for deleterious lichen invasion of the wall paintings inside the Convent.

Architecture↗

PubMed1999

Biodeterioration of granite monuments by Ochrolechia parella (L.) mass: an FT Raman spectroscopic study.

Ochrolechia parella is one of the most abundant lichens colonizing granite monuments in the region of Galicia (N.W. Spain). Its interaction with granite used in the construction of four ancient monuments was studied using FT Raman spectroscopy to evaluate the production of calcium oxalate by this lichen and the relationship of this production with different environmental conditions, particularly humidity. The results obtained showed that Ochrolechia parella is an aggressive colonizer, causing chemical disturbances to the granite through the formation of both calcium oxalate monohydrate and dihydrate. Apothecial development appears to be related to the production of calcium oxalate, and humidity determines the state of hydration of the calcium oxalate in the thallus.

Architecture↗

PubMed1999

A decade of doctoral research in nutrition.

OBJECTIVE: To describe North American dissertation research in human nutrition from 1986 through 1995. DESIGN: A census collection. SUBJECTS/SETTING: The unit of observation was the dissertation abstract submitted to Dissertation Abstracts International for the years 1986 through 1995. Only dissertations written in English with a human nutrition subject code (0570) that lead to a PhD, DrPH, EdD, or ScD at a North American university were included (N = 2,044). Abstracts were reviewed by 2 raters who extracted pertinent data on variables describing the dissertation research (e.g., topic of dissertation, type of sample). ANALYSES: Analyses were descriptive. RESULTS: The majority (n = 1,147) of doctoral dissertations were completed by female students. Male students were more likely to study in vitro samples than female students (11% vs 4%) and female students were more likely to study human subjects (64%). Male students tended to have male advisers, although overall male advisers appeared to predominate (34% men, 24% women, 42% unknown or missing). Topic areas for dissertation work reflected gender differences. Popular topics for dissertation research have changed over time; biochemical-, micronutrient-, and obesity-related research decreased and research in development of theoretical constructs and examination of dietary habits of selected groups increased. CONCLUSIONS: From 1986 through 1995 there was an increase in the proportion of female doctoral students. Female and male students varied in the type of sample studied, gender of advisers, age group of human subjects, and topics of their dissertations. Universities emphasized different topic areas and methodologies. There appears to have been an increase in areas of applied research (e.g., dietary habits) and a decrease in basic science topic areas (e.g., micronutrients) over the 10-year period examined.

Academic Dissertations as Topic↗

PubMed1998

Thermally induced molecular disorder in human stratum corneum lipids compared with a model phospholipid system; FT-Raman spectroscopy.

The molecular basis of lipid packing in human stratum corneum and a model phospholipid system has been studied as a function of temperature using Fourier Transform (FT) Raman spectroscopy. Thermally induced molecular rearrangements of the model lipid system, dipalmitoylphosphatidyl choline (DPPC), and stratum corneum were investigated using FT Raman spectroscopy coupled to a heating chamber. Spectra were recorded for a range of sample temperatures and the results for the two systems were compared, producing previously unreported information of the thermal behaviour for the different systems. Discrete thermal events were recorded for both systems by plotting band separation of the lipid v(CH2) symmetric and asymmetric stretching modes against temperature. The main thermal events observed for DPPC included a 'pre-melting' between 37 and 39 degrees C, the main transition observed between 41 and 42 degrees C, a 'post-transition' between 42 and 43 degrees C and three minor transitions at 58-60, 65-70 and 75-80 degrees C. No evidence was found for the pre-transition of DPPC, previously observed at 34-35 degrees C. The main transitions for human stratum corneum were observed at 35-45, 55, 72 and 83 degrees C, measured from lipid CH2 stretching and bending vibrations. The keratin thermal transition at about 100 degrees C exerted little effect on the lipid bands and no characterisable structural changes were reflected in the keratotic bands.

1,2-Dipalmitoylphosphatidylcholine↗

PubMed1998

FT-Raman spectroscopic study of keratotic materials: horn, hoof and tortoiseshell.

The Fourier-Transform Raman spectra of some mammalian and reptilian keratins, horn, hoof and tortoiseshell, have been analysed and used for the construction of a database for the identification of highly keratotic samples. The samples investigated were; bovine keratin and hoof, Texas Longhorn cattle horn, kudu horn, tortoiseshell and human finger nail. Significant spectral differences were observed in the 1000-400 cm-1 wavenumber range, which included the conformationally important v(SS) and v(CS) features around 500 and 640 cm-1, respectively. The amide I (1650 cm-1) and amide III (1260 cm-1) bands confirmed that the reptilian keratin studied exists in the beta-sheet conformation, whilst mammalian keratins are predominantly laid down in an alpha-helical conformation. The FT-Raman spectral differences particularly between the horn and hoof specimens are very useful for the non-destructive characterisation of artefacts and provides a novel application of the technique.

Animals↗

PubMed1998

Interaction of salicylic acid with verrucae assessed by FT-Raman spectroscopy.

FT-Raman spectroscopy has been used to investigate treated verrucae (warts from the sole of the foot) with a local application of a salicylic acid paint. Differences in the molecular structure of the stratum corneum across the verruca sample were observed, and by comparison with normal and hyperkeratotic skin it was concluded that the tissue around the edges of the verrucae was typically hyperkeratotic skin. In the centre of the verruca, the molecular structure of the skin was altered showing evidence of the interaction with salicylic acid. Salicylic acid was not observed in its characteristic dimerised acid structure, but spectroscopic evidence suggested that fission of the intermolecular H-bonding essentially cleaved the dimer. Observed changes in the v(CCO) stretching mode of the carboxyl and hydroxyl groups indicate the inter H-bonds have broken. These spectral changes are believed to be more consistent with salicylic acid bonding within the human papillomavirus-containing verruca tissue rather than simple acid dissociation upon dissolution in water within the tissue. No evidence for the presence of the other paint components, lactic acid and flexible collodion, was found in the verrucae spectra. This Raman approach may help to elucidate the molecular basis for therapeutic agents interacting with diseased skin.

Humans↗

PubMed1997

Fourier-transform Raman spectroscopic study of human hair.

Fourier-transform Raman microscopic spectra of normal, untreated and bleached hair fibres are presented. Vibrational assignments are made and differences are ascribed to the production of cysteic acid from cysteine. Changes in conformation associated with the disulphide bond in the keratotic component are noted from the v(CSSC) vibrational modes at wave numbers near 500 cm-1. Raman spectra of hair root ends have also been investigated with a diminution in cysteine content being observed. Application of the technique to the biomedical investigation of healthy and diseased hair is proposed.

Adolescent↗

PubMed1997

FT Raman microscopy of untreated natural plant fibres.

The application of FT-Raman microscopy to the non-destructive analysis of natural plant fibres is demonstrated with samples of flax, jute, ramie, cotton, kapok, sisal and coconut fibre. Vibrational assignments are proposed and characteristic features of each material are presented. Samples were not pre-treated chemically before analysis and were used directly from their respective storage collection; the adaptation of the Raman microscopic technique to the identification of specimens of natural fibres in archaeological burial sites is explored for its forensic potential.

Cellulose↗

PubMed1997

Fourier-transform Raman spectra of ivory. III: Identification of mammalian specimens.

The FT-Raman spectra of six mammalian ivories, other than elephant and mammoth, are presented and spectral differences formulated into a protocol for the identification of animal species from the ivory samples. In this study, sperm whale, walrus, wart hog, narwhal, hippopotamus and domestic pig are considered. The results, which are obtained non-destructively from a variety of specimens, suggest that FT-Raman spectroscopy provides a potentially useful method for the identification of mammalian ivory.

Animals↗

PubMed1997

Fourier-transform Raman spectroscopy of mammalian and avian keratotic biopolymers.

The FT-Raman spectra of mammalian and avian keratotic biopolymers have been recorded, including bull's horn, cat's claw, bird's feather quill, pheasant's beak and compared with the hard keratinous tissue, human nail and callus. Although there were similarities in all the spectra. particularly in the v(CH) stretching region, the 1450-1100 cm-1 region exhibited some differences ascribed to intramolecular skeletal backbone conformational changes. Of particular significance for human, mammalian and avian samples in the 1000-400 cm-1 wavenumber region were differences in the structurally important v(SS) and v(CS) bands, near 500 cm-1 and 630 cm-1 respectively. The amide I and III modes near 1650 and 1250 cm-1 respectively, demonstrate that the mammalian keratins studied exist predominantly in the alpha-helical conformation, whereas the avian keratins adopt the beta-sheet structure as the dominant conformation.

Amino Acids↗

PubMed1996

Oxybenzone oxidation following solar irradiation of skin: photoprotection versus antioxidant inactivation.

We used noninvasive Fourier transform (FT) Raman spectroscopy to follow the fate of the broadly used ultraviolet UVA sun blocker, oxybenzone, after topical application to the skin. Our results showed that oxybenzone is rapidly photo-oxidized, yielding oxybenzone semiquinone, a potent electrophile, which reacts with thiol groups on important anti-oxidant enzymes and substrates, such as thioredoxin reductase and reduced glutathione, respectively. Although oxybenzone is an excellent broad spectrum UVA filter, its rapid oxidation followed by the inactivation of important antioxidant systems indicates that this substance may be rather harmful to the homeostasis of the epidermis. Furthermore, these results demonstrate that FT-Raman spectroscopy is a useful method for studying the transport and metabolism of active ingredients in topical preparations.

Administration, Topical↗

PubMed1995

Sucrose reduces the efficiency of protein denaturation by a chaotropic agent.

Sugars and polyols are used to stabilize proteins. The degree of stabilization conferred on a model protein by sucrose was calculated in terms of the free energy of folding. Phosphoglycerate kinase (PGK) was denatured by guanidine hydrochloride (GuHCl) in different sucrose concentrations. The linear extrapolation method [1,2] was used to calculate the free energy of folding in the absence of denaturant. Although sucrose increased the concentration of GuHCl required to unfold the protein, the free energy of folding in water was unchanged. In order to probe the nature of the stabilizing effect of sucrose, an FT-Raman spectroscopic study of denaturant-polyol systems was undertaken. Investigations of interactions between GuHCl, urea or formamide and polyhydric compounds, revealed no evidence for hydrogen bonding or dipole-dipole associations. Polyhydric compounds caused minor changes in denaturant spectra although the converse was not observed. The structure of deuterated water changed on addition of denaturants. For non-ionic denaturants, addition of polyhydric solutes countered this change in water structure. Thus polyhydric compounds oppose the effect of denaturants on water structure. The observed increase in GuHCl concentration required to unfold PGK in the presence of sucrose may be attributed to this property of sucrose.

Formamides↗

PubMed1995

The 'Iceman': molecular structure of 5200-year-old skin characterised by Raman spectroscopy and electron microscopy.

The molecular state of about 5200-year-old skin from the so-called 'Iceman' (Similaun man or Otzi) has been characterised using Fourier transform Raman spectroscopy, and has been compared with that of contemporary man. Contemporary skin was also freeze-dried (to mimic the conditions under which the ancient skin was preserved) and its molecular structure was compared with that of Iceman skin. The results showed that the proteinaceous moiety of the ancient skin had degraded considerably and, although olefinic bonds had probably oxidised, the lipoidal component was largely unaltered. Electron microscopical comparisons of Iceman and contemporary skin showed that the gross structure of Iceman skin had survived essentially intact for five millennia.

Animals↗

PubMed1994

Comparison of Fourier transform Raman spectra of mammalian and reptilian skin.

Human skin offers potential advantages for the administration of therapeutic agents for both local and systemic use. However, in studies of transdermal drug delivery, problems with the supply, storage, and use of human tissue have encouraged workers to seek alternative animal materials to model drug diffusion across human skin. We obtained Fourier transform Raman spectra from mammalian (human and pig) and reptilian (snake) skins, and considered structural dissimilarities in the light of differences observed in the diffusion of drugs across the tissues.

Animals↗