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Haruta, N., & Kitagawa, T. (2002). Time-resolved UV resonance Raman investigation of protein folding using a rapid mixer: characterization of kinetic folding intermediates of apomyoglobin. Biochemistry, 41(21), 6595–6604.
Abstract: The 244-nm excited transient UV resonance Raman spectra are observed for the refolding intermediates of horse apomyoglobin (h-apoMb) with a newly constructed mixed flow cell system, and the results are interpreted on the basis of the spectra observed for the equilibrium acid unfolding of the same protein. The dead time of mixing, which was determined with the appearance of UV Raman bands of imidazolium upon mixing of imidazole with acid, was 150 micros under the flow rate that was adopted. The pH-jump experiments of h-apoMb from pH 2.2 to 5.6 conducted with this device demonstrated the presence of three folding intermediates. On the basis of the analysis of W3 and W7 bands of Trp7 and Trp14, the first intermediate, formed before 250 micros, involved incorporation of Trp14 into the alpha-helix from a random coil. The frequency shift of the W3 band of Trp14 observed for this process was reproduced with a model peptide of the A helix when it forms the alpha-helix. In the second intermediate, formed around 1 ms after the start of refolding, the surroundings of both Trp7 and Trp14 were significantly hydrophobic, suggesting the formation of the hydrophobic core. In the third intermediate appearing around 3 ms, the hydrophobicity was relaxed to the same level as that of the pH 4 equilibrium intermediate, which was investigated in detail with the stationary state technique. The change from the third intermediate to the native state needs more time than 40 ms, while the appearance of the native spectrum after the mixing of the same solutions was confirmed separately.
Keywords: Animals; Apoproteins/*chemistry; Circular Dichroism; Holoenzymes/chemistry; Horses; Hydrochloric Acid/chemistry; Hydrogen-Ion Concentration; Imidazoles/chemistry; Kinetics; Models, Molecular; Myoglobin/*chemistry; Peptide Fragments/chemistry; *Protein Folding; Protein Structure, Secondary; Spectrum Analysis, Raman/*methods; Tryptophan/*chemistry; Ultraviolet Rays; Whales
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Griffin, B. (2002). The use of fecal markers to facilitate sample collection in group-housed cats. Contemp Top Lab Anim Sci, 41(2), 51–56.
Abstract: The provision of proper social housing is a priority when designing an experiment using domestic cats as laboratory animals. When animals are group-housed, studies requiring analysis of stool samples from individual subjects pose difficulty in sample collection and identification. In this study, commercially available concentrated food colorings (known as bakers pastes) were used as fecal markers in group-housed cats. Cats readily consumed 0.5 ml of bakers paste food coloring once daily in canned cat food. Colorings served as fecal markers by imparting a distinct color to each cat s feces, allowing identification in the litter box. In addition, colored glitter (1/8 teaspoon in canned food) was fed to cats and found to be a reliable fecal marker. Long-term feeding of colorings and glitter was found to be safe and effective at yielding readily identifiable stools.
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Gulotta, M., Gilmanshin, R., Buscher, T. C., Callender, R. H., & Dyer, R. B. (2001). Core formation in apomyoglobin: probing the upper reaches of the folding energy landscape. Biochemistry, 40(17), 5137–5143.
Abstract: An acid-destabilized form of apomyoglobin, the so-called E state, consists of a set of heterogeneous structures that are all characterized by a stable hydrophobic core composed of 30-40 residues at the intersection of the A, G, and H helices of the protein, with little other secondary structure and no other tertiary structure. Relaxation kinetics studies were carried out to characterize the dynamics of core melting and formation in this protein. The unfolding and/or refolding response is induced by a laser-induced temperature jump between the folded and unfolded forms of E, and structural changes are monitored using the infrared amide I' absorbance at 1648-1651 cm(-1) that reports on the formation of solvent-protected, native-like helix in the core and by fluorescence emission changes from apomyoglobin's Trp14, a measure of burial of the indole group of this residue. The fluorescence kinetics data are monoexponential with a relaxation time of 14 micros. However, infrared kinetics data are best fit to a biexponential function with relaxation times of 14 and 59 micros. These relaxation times are very fast, close to the limits placed on folding reactions by diffusion. The 14 micros relaxation time is weakly temperature dependent and thus represents a pathway that is energetically downhill. The appearance of this relaxation time in both the fluorescence and infrared measurements indicates that this folding event proceeds by a concomitant formation of compact secondary and tertiary structures. The 59 micros relaxation time is much more strongly temperature dependent and has no fluorescence counterpart, indicating an activated process with a large energy barrier wherein nonspecific hydrophobic interactions between helix A and the G and H helices cause some helix burial but Trp14 remains solvent exposed. These results are best fit by a multiple-pathway kinetic model when U collapses to form the various folded core structures of E. Thus, the results suggest very robust dynamics for core formation involving multiple folding pathways and provide significant insight into the primary processes of protein folding.
Keywords: Animals; Apoproteins/*chemistry; Computer Simulation; Horses; Hydrogen-Ion Concentration; Kinetics; Models, Molecular; Myoglobin/*chemistry; *Protein Folding; Protein Structure, Secondary; Protein Structure, Tertiary; Spectrometry, Fluorescence/instrumentation/methods; Thermodynamics; Tryptophan/chemistry
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Keay, J. M., Singh, J., Gaunt, M. C., & Kaur, T. (2006). Fecal glucocorticoids and their metabolites as indicators of stress in various mammalian species: a literature review. J Zoo Wildl Med, 37(3), 234–244.
Abstract: Conservation medicine is a discipline in which researchers and conservationists study and respond to the dynamic interplay between animals, humans, and the environment. From a wildlife perspective, animal species are encountering stressors from numerous sources. With the rapidly increasing human population, a corresponding increased demand for food, fuel, and shelter; habitat destruction; and increased competition for natural resources, the health and well-being of wild animal populations is increasingly at risk of disease and endangerment. Scientific data are needed to measure the impact that human encroachment is having on wildlife. Nonbiased biometric data provide a means to measure the amount of stress being imposed on animals from humans, the environment, and other animals. The stress response in animals functions via glucocorticoid metabolism and is regulated by the hypothalamic-pituitary-adrenal axis. Fecal glucocorticoids, in particular, may be an extremely useful biometric test, since sample collection is noninvasive to subjects and, therefore, does not introduce other variables that may alter assay results. For this reason, many researchers and conservationists have begun to use fecal glucocorticoids as a means to measure stress in various animal species. This review article summarizes the literature on many studies in which fecal glucocorticoids and their metabolites have been used to assess stress levels in various mammalian species. Variations between studies are the main focus of this review. Collection methods, storage conditions, shipping procedures, and laboratory techniques utilized by different researchers are discussed.
Keywords: Animals; *Animals, Wild/metabolism; Chromatography, High Pressure Liquid/methods/veterinary; Circadian Rhythm; Conservation of Natural Resources; *Ecosystem; Feces/*chemistry; Glucocorticoids/*analysis/metabolism; Humans; Seasons; Species Specificity; Specimen Handling/methods/veterinary; Stress, Psychological/*metabolism
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Husted, L., Andersen, M. S., Borggaard, O. K., Houe, H., & Olsen, S. N. (2005). Risk factors for faecal sand excretion in Icelandic horses. Equine Vet J, 37(4), 351–355.
Abstract: REASONS FOR PERFORMING STUDY: Sandy soil is often mentioned as a risk factor in the development of sand-related gastrointestinal disease (SGID) in the horse. There are other variables, but few studies confirm any of these. OBJECTIVE: To investigate soil type, pasture quality, feeding practice in the paddock, age, sex and body condition score as risk factors for sand intake in the horse. METHODS: Faeces were collected from 211 Icelandic horses on 19 different studs in Denmark together with soil samples and other potential risk factors. Sand content in faeces determined by a sand sedimentation test was interpreted as evidence of sand intake. Soil types were identified by soil analysis and significance of the data was tested using logistic analysis. RESULTS: Of horses included in the study, 56.4% showed sand in the faeces and 5.7% had more than 5 mm sand as quantified by the rectal sleeve sedimentation test. Soil type had no significant effect when tested as main effect, but there was interaction between soil type and pasture quality. Significant interactions were also found between paddock feeding practice and pasture quality. CONCLUSION: To evaluate the risk of sand intake it is important to consider 3 variables: soil type, pasture quality and feeding practice. Pasture quality was identified as a risk factor of both short and long grass in combination with sandy soil, while clay soil had the lowest risk in these combinations. Feeding practice in the paddock revealed feeding directly on the ground to be a risk factor when there was short (1-5 cm) or no grass. Also, no feeding outdoors increased the risk on pastures with short grass, while this had no effect in paddocks with no grass. More than 50% of all horses investigated in this study had sand in the faeces. POTENTIAL RELEVANCE: The identification of risk factors is an important step towards prevention of SGID. Further research is necessary to determine why some horses exhibit more than 5 mm sand in the sedimentation test and whether this is correlated with geophagic behaviour.
Keywords: Animal Feed; Animal Husbandry/methods; Animals; Denmark; Feces/*chemistry; Female; Gastrointestinal Diseases/epidemiology/etiology/prevention & control/veterinary; Horse Diseases/epidemiology/etiology/prevention & control; Horses/*metabolism; Logistic Models; Male; Pilot Projects; *Poaceae/growth & development; Risk Factors; Silicon Dioxide/administration & dosage/adverse effects/*analysis; Soil/*analysis
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Birch, H. L., Bailey, A. J., & Goodship, A. E. (1998). Macroscopic 'degeneration' of equine superficial digital flexor tendon is accompanied by a change in extracellular matrix composition. Equine Vet J, 30(6), 534–539.
Abstract: Injuries to the superficial digital flexor tendon are common in horses required to gallop and jump at speed. Partial rupture of this tendon usually occurs in the central core of the midmetacarpal region and may be preceded by localised degenerative changes. Post mortem examination of apparently normal equine flexor tendons has revealed an abnormal macroscopic appearance in the central core, characterised by a reddish discolouration. We have previously shown that there is also physical damage to the collagen fibres. In the present study we tested the hypothesis that the abnormal appearance is accompanied by changes in the composition of the extracellular matrix of the tendon. Biochemical analysis of the extracellular matrix demonstrated an increase in total sulphated glycosaminoglycan content, increase in the proportion of type III collagen and decrease in collagen linked fluorescence in the central core of 'degenerated' tendons relative to tissue from the peripheral region of the same tendon. Dry matter content and total collagen content were not significantly different between tendon zones or normal and 'degenerated' tendons. These changes suggest a change in cell metabolism and matrix turnover in the central core of the tendon and are likely to contribute to a decrease in mechanical properties in this part of the tendon, predisposing to the characteristic partial rupture of the tendon.
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Nicol, C. J., Yoon, M., Ward, J. M., Yamashita, M., Fukamachi, K., Peters, J. M., et al. (2004). PPARgamma influences susceptibility to DMBA-induced mammary, ovarian and skin carcinogenesis. Carcinogenesis, 25(9), 1747–1755.
Abstract: Peroxisome proliferator-activated receptor gamma (PPARgamma), a member of the nuclear receptor superfamily, plays a role in adipocyte differentiation, type II diabetes, macrophage response to inflammation and is suggested to influence carcinogen-induced colon cancer. Studies done in vitro and in vivo also revealed that PPARgamma ligands might promote differentiation and/or regression of mammary tumors. To directly evaluate the role of PPARgamma in mammary carcinogenesis, PPARgamma wild-type (+/+) or heterozygous (+/-) mice were administered 1 mg 7,12-dimethylbenz[a]anthracene (DMBA) by gavage once a week for 6 weeks and followed for a total of 25 weeks. Compared with congenic PPARgamma(+/+) littermate controls, PPARgamma(+/-) mice had early evidence for increased susceptibility to DMBA-mediated carcinogenesis based on a 1.6-fold increase in the percentage of mice with skin papillomas, as well as a 1.7-fold increase in the numbers of skin papillomas per mouse (P < 0.05). Similarly, PPARgamma(+/-) mice also had a 1.5-fold decreased survival rate (P = 0.059), and a 1.7-fold increased incidence of total tumors per mouse (P < 0.01). Moreover, PPARgamma(+/-) mice had an almost 3-fold increase in mammary adenocarcinomas (P < 0.05), an over 3-fold increase in ovarian granulosa cell carcinomas (P < 0.05), an over 3-fold increase in malignant tumors (P < 0.02) and a 4.6-fold increase in metastatic incidence. These results are the first to demonstrate an increased susceptibility in vivo of PPARgamma haploinsufficiency to DMBA-mediated carcinogenesis and suggest that PPARgamma may act as a tumor modifier of skin, ovarian and breast cancers. The data also support evidence suggesting a beneficial role for PPARgamma-specific ligands in the chemoprevention of mammary, ovarian and skin carcinogenesis.
Keywords: 9,10-Dimethyl-1,2-benzanthracene/*toxicity; Animals; DNA Primers/chemistry; Disease Susceptibility; Female; Heterozygote; Humans; Mammary Neoplasms, Experimental/chemically induced/*pathology; Mice; Ovarian Neoplasms/chemically induced/*pathology; RNA, Messenger/genetics/metabolism; Receptors, Cytoplasmic and Nuclear/genetics/*physiology; Reverse Transcriptase Polymerase Chain Reaction; Skin Neoplasms/chemically induced/*pathology; Survival Rate; Transcription Factors/genetics/*physiology; Zinc Fingers
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Abbruzzetti, S., Viappiani, C., Sinibaldi, F., & Santucci, R. (2004). Kinetics of histidine dissociation from the heme Fe(III) in N-fragment (residues 1-56) of cytochrome c. Protein J, 23(8), 519–527.
Abstract: We have here investigated the dissociation kinetics of the His side chains axially ligated to the heme-iron in the ferric (1-56 residues) N-fragment of horse cyt c. The ligand deligation induced by acidic pH-jump occurs as a biexponential process with different pre-exponential factors, consistent with a structural heterogeneity in solution and the presence of two differently coordinated species. In analogy with GuHCl-denatured cyt c, our data indicate the presence in solution of two ferric forms of the N-fragment characterized by bis-His coordination, as summarized in the following scheme: His18-Fe(III)-His26 <==> His18-Fe(III)-His33. We have found that the pre-exponential factors depend on the extent of the pH-jump. This may be correlated with the different pKa values shown by His26 and His33; due to steric factors, His26 binds to the heme-Fe(III) less strongly than His33, as recently shown by studies on denatured cyt c. Interestingly, the two lifetimes are affected by temperature but not by the extent of the pH-jump. The lower pKa for the deligation reaction required the use of an improved laser pH-jump setup, capable of inducing changes in H+ concentration as large as 1 mM after the end of the laser pulse. For the ferric N-fragment, close activation entropy values have been determined for the two histidines coordinated to the iron; this result significantly differs from that for GuHCl-denatured cyt c, where largely different values of activation entropy were calculated. This underlines the role played by the missing segment (residues 57-104) peptide chain in discriminating deligation of the “nonnative” His from the sixth coordination position of the metal.
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Miksovska, J., & Larsen, R. W. (2003). Photothermal studies of pH induced unfolding of apomyoglobin. J Protein Chem, 22(4), 387–394.
Abstract: Conformational dynamic and enthalpy changes associated with pH induced unfolding of apomyoglobin were studied using photoacoustic calorimetry and photothermal beam deflection methods. The transition between the native state and the I intermediate was induced by a nanosecond pH jump from o-nitrobenzaldehyde photolysis. Deconvolution of photoacoustic waves indicates two kinetic processes. The fast phase (T < 50 ns) is characterized by a volume expansion of 8.8 ml mol(-1). This process is followed by a volume contraction of about -22 ml mol(-1) (tau approximately 500 ns). Photothermal beam deflection measurements do not reveal any volume changes on the time scale between approximately 100 micros and 5 ms. We associate the volume contraction with structural changes occurring during the transition between the native state and the I intermediate. The lack of any processes on the ms time scale may indicate the absence of structural events involving larger conformational changes of apomyoglobin after the pH jump.
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Aviad, A. D., & Houpt, J. B. (1994). The molecular weight of therapeutic hyaluronan (sodium hyaluronate): how significant is it? J Rheumatol, 21(2), 297–301.
Abstract: Various molecular weight hyaluronic acid (HA) preparations have been injected into joints for the treatment of human and equine osteoarthritis. A therapeutic advantage has been claimed for commercial products with a molecular weight in the range found in normal synovial fluid (SF), compared to lower molecular weight products. But a correlation between molecular weight and efficacy is not borne out by an analysis of the available literature on clinical results. SF viscosity, HA concentration, HA molecular weight and rate of synthesis in joint disease. It is proposed that the beneficial effect of injected HA in joint disease may be due to pharmacological rather than to physical properties.
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