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Facile route to ultraflat SAM-protected gold surfaces by "amphiphile splitting".
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Electron transfer in a Hg-SAM//SAM-Hg junction mediated by redox centers.
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Molecular-recognition characteristics of SAM-binding riboswitches.
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Surface reactions on demand: electrochemical control of SAM-based reactions.
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Analytical cytogenetics. Dedicated to the memory of Sam Latt. A symposium of the 13th International Meeting of the Society for Analytical Cytology. Breckenridge, Colorado, September 4-9, 1988. Proceedings.
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Theoretical analysis of adsorption thermodynamics for hydrophobic peptide residues on SAM surfaces of varying functionality.
At a fundamental level, protein adsorption to a synthetic surface must be strongly influenced by the interaction between the peptide residues presented by the protein's surface (primary protein structure) and the functional groups presented by the synthetic surface. In this study, semi-empirical molecular modeling was used along with experimental wetting data to theoretically approach protein adsorption at this primary structural level. Changes in enthalpy, entropy, and Gibbs free energy were calculated as a function of residue-surface separation distance for the adsorption of individual hydrophobic peptide residues (valine, leucine, phenylalanine) on alkanethiol self-assembled monolayers on gold [Au-S(CH(2))(15)-X; X = CH(3), OH, NH(3)(+), COO(-)]. The results predict that the adsorption of each type of hydrophobic residue is energetically favorable and entropy dominated on a methyl-terminated hydrophobic surface, energetically unfavorable and enthalpy dominated on a hydroxyl-terminated neutral hydrophilic surface, and very slightly favorable to unfavorable and enthalpy dominated on charged surfaces. These theoretical results provide a basis for understanding some of the fundamental effects governing protein adsorption to synthetic surfaces. This level of understanding is needed for the proactive design of surfaces to control protein adsorption and subsequent cellular response for both implant and tissue engineering applications.
Ultrastructural and permeability features of microvessels in the periventricular area of senescence-accelerated mice (SAM).
Brain transfer of intravenously injected horseradish peroxidase (HRP) and the ultrastructural features of the vessels were examined in periventricular areas in senescence-accelerated mice (SAMP8), which show age-related deficits in learning and memory, and senescence-accelerated resistant mice (SAMR1), which do not show age-related deficits. In all mice examined with light microscopy, staining reaction for HRP was seen in the periventricular area adjacent to the medial side of the lateral ventricle. Electron microscopic examination in the periventricular area of young and old mice of both strains showed that the staining reaction for HRP appeared in the vesicular profiles of the endothelial cytoplasm, the cytoplasm of the perivascular cells, the basal lamina, and the adjoining extracellular spaces of the white matter, suggesting an incomplete blood-brain barrier (BBB) in the periventricular white matter. In addition, irregularly thickened endothelial cell cytoplasm, membranous inclusions within the basal lamina, and electron-dense endothelial cell cytoplasm were occasionally seen in aged SAMP8 mice. These findings were not observed in 3-month-old SAMP8 mice and 3- and 13-month-old SAMR1 mice. Perivascular collagen deposits were also frequently seen in aged SAMP8 mice. These findings indicate that the endothelial cells and pericytes in the periventricular white matter in aged SAMP8 mice have an ultrastructure with damaged BBB function. Intravascular substances can easily penetrate the periventricular white matter and the BBB of the vessels in the area can be deteriorated with aging in SAMP8 mice.
Effect of Choto-san, a Kampo medicine, on impairment of passive avoidance performance in senescence accelerated mouse (SAM).
Effect of Choto-san (TJ-47), a Kampo medicine, on impairment of learning performance was evaluated by means of a step-through passive avoidance task in SAMP8 mice, a senescence-prone substrain. Tokishakuyaku-san (TJ-23), another Kampo medicine, was also employed for comparison. SAMP8 mice at the age of 10-12 months showed a poorer passive avoidance response than SAMR1 mice, a senescence-resistant substrain, in the memory-retention test, but not in the memory-acquisition test. Improved response in the memory-retention test was observed in SAMP8 mice treated with TJ-47, and almost equal degree of improvement was also observed after treatment with TJ-23. These results suggest that a long-term administration of Choto-san could improve to some extent the impairment of memory caused by aging.
Sam Greenhouse's scholarly contributions to human aging studies.
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Comment on Tachibana's reply to Buelke-Sam et al., Springer et al., and Gaylor regarding reply to: comments on "Behavioral teratogenic effect of methylmercury and d-amphetamine: meta-analysis and power analysis of data from the Collaborative Behavioral Teratology Study of National Center for Toxicological Research.
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Protein alterations in age-related cataract associated with a persistent hyaloid vascular system in senescence-accelerated mouse (SAM).
The occurrence of age-related cataract associated with a persistent hyaloid vascular system is the most prominent feature in SAMP9, an inbred strain of Senescence-accelerated Mouse. To examine the cataractogenesis, we analysed protein changes in the process of cataract formation in the lens. The cataractous lenses showed a striking decrease in water-soluble protein content, in contrast to increases in the amount of water insoluble protein. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and Western blots of water-soluble protein in the cataractous lenses showed additional high molecular weight beta-crystallin proteins of about 43 kDa, concomitant with decreased amounts of 29-kDa and 31-kDa beta-crystallins and 21-kDa gamma-crystallin, as compared with findings in normal lenses. Although there was no apparent difference between the patterns of SDS-PAGE of urea-soluble and urea-insoluble proteins isolated from cataractous and normal lenses, slightly increased reactivity of bands around 43 kDa against anti-beta-crystallin antibody was observed in cataractous lenses. The calcium content was elevated and activity of transglutaminase was increased in the cataractous lenses. While the molecular weight of beta-crystallin polymers cross-linked in vitro by exogenous transglutaminase was not completely compatible with those of high molecular weight beta-crystallins observed in the cataractous lenses, these findings do suggest the contribution of this enzyme to production of high molecular weight beta-crystallins and to insolubilization of these proteins in the cataractous lenses in SAMP9.
Draw It again Sam: the effect of drawing on children's suggestibility and source monitoring ability.
Preschool children (aged 3 to 6 years) participated in a magic show. Later, the children were given repeated true and false reminders about the show. Half the children were asked to draw these true and false reminders (drawing condition) and half the children were asked questions about the reminders but not to draw them (question condition). Later, children in the drawing condition had better recall of true reminders than children in the question group; however, children in the drawing group also recalled more false reminders than children in the question group. Finally, although children in the drawing group had better memory of the source of the reminders than children in the question group, both groups equally reported that the false reminders actually happened.
Effect of Cladribine, fludarabine, and 5-aza-deoxycytidine on S-adenosylmethionine (SAM) and nucleotides pools in stimulated human lymphocytes.
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Immunocytochemical evaluation of the blood-brain barrier to endogenous albumin in the olfactory bulb and pons of senescence-accelerated mice (SAM).
The blood-brain barrier (BBB) to endogenous albumin was studied in the olfactory bulb and pons of the senescence-accelerated prone (SAMP8) mouse and senescence-accelerated resistant (SAMR1) mouse strains by using a quantitative immunocytochemical procedure. Ultrathin sections of Lowicryl K4M-embedded samples were exposed to anti-mouse albumin antiserum followed by protein A-gold. Morphometric analysis of the electron micrographs revealed that in the olfactory bulb of both groups of animals, especially in the internal granular layer, some percentage of capillaries and slightly larger microvessels showed leakage of albumin. However, this percentage was larger in SAMP8 than in SAMR1 mice. In the pons, no significant differences in the permeability of blood microvessels were observed in both groups of mice, although a small fraction of capillaries in SAMP8 mice showed limited extravasation of blood plasma albumin. These observations indicate that the BBB in the olfactory bulb of control and SAMP8 mice is not as tight as it is in the pons or in the previously examined cerebral cortex. The labelling density of the neuropil was slightly higher than in the cerebral cortex, suggesting that albumin may have extravasated locally, in addition to having acces to the parenchyma of the olfactory bulb and pons from neighbouring areas supplied with the non-BBB-type of microvasculature. Furthermore, the data obtained suggest that there is limited (segmental), premature age-related impairment of the BBB function in SAMP8 mice.
re: Gastaldelli A, Ferrannini E, Miyazaki Y, Matsuda M, DeFronzo RA (2004) Beta cell dysfunction and glucose intolerance: results from the San Antonio metabolism (SAM) study. Diabetologia 47:31-39.
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Ultrastructural and permeability features of microvessels in the olfactory bulbs of SAM mice.
The ultrastructural features of microvessels showing increased permeability to intravenously injected horseradish peroxidase (HRP) were examined in the olfactory bulbs of senescence-accelerated prone mice (SAMP8), which showed age-related deficits in learning and memory, and senescence-accelerated resistant mice (SAMR1), which did not show the age-related deficits. HRP was visualized with tetramethyl benzidine (TMB) and diaminobenzidine (DAB) for light and electron microscopic examination, respectively. In the olfactory bulbs of 13-month-old SAMP8 mice, the staining reaction with TMB for HRP appeared in the neuropil of central area (granule cell layer and subependymal layer), in the pia mater and in the vascular wall. Some vessels located in the central area showed several changes observed at the ultrastructural level. The cytoplasm of the endothelial cells, especially in the arterioles, was segmentally thickened and contained numerous vesicles and vacuoles, some of which were HRP positive. The endothelial cell surface was occasionally undulated with microvillous protrusions. Membranous inclusions within the basal lamina, suggesting the cellular (presumably pericytal) degeneration, were frequently observed, especially in venules. The collagen deposits were occasionally observed in the subendothelial space of some vessels. Perivascular cells with vacuolated inclusions or lipid-like droplets were present around some vessels in the central area of the olfactory bulbs of aged SAMP8 mice. On the other hand, in the microvessels located in the areas negative for HRP-TMB reaction, except the vessel walls, the cytoplasm of the endothelial cells with smooth luminal surface was flattened and some vesicles located there contained HRP-DAB reaction product. Weak staining reaction with TMB for HRP appeared also in the central area of the olfactory bulbs of 3-month-old SAMP8 mice and 3- and 13-month-old SAMR1 mice. The cytoplasm of the endothelial cells in the olfactory bulbs of these mice was focally thickened and contained some cytoplasmic vesicles. Occasionally, the endothelial cell surface was moderately undulated with few microvillous protrusions. Membranous inclusions within the basal lamina were not observed in these animals. These findings indicate that the endothelial cells and pericytes in some vessels located in the central area of the olfactory bulb of aged SAMP8 mice, which show staining reaction with TMB for HRP, are ultrastructurally changed, suggesting their altered functions.
Carnosine-induced changes in the development of spermatogenic epithelial cells in senescence accelerated SAM mice.
Carnosine significantly increased the number of spermatogonia and Sertoli cells in mice prone (SAMP1) and resistant (SAMR1) to accelerated aging and appreciably reduced cell yield in meiosis and spermiogenesis in SAMP1 mice. In experimental SAMP1 mice catastrophic changes in the number of gametes were paralleled by intensive degradation of the spermatogenic epithelium. In SAMR1 mice treated with carnosine highly ordered spermatogenic structure was preserved.