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At least 109 records · Page 6Linked to original sources
PubMed1990

Effects of Kamikihi-To, a traditional Chinese medicine, on passive and conditioned avoidance performance impairment in senescence accelerated mouse (SAM).

Effects of Kamikihi-To (KMK), a traditional Chinese medicine (Chinese name: Jia-Wei-Gui-Pi-Tang), on learning performance impairment caused by aging were evaluated in senescence accelerated mice (SAM). Normal diet containing 8% KMK extract was given to SAM-P/8, a senile-prone strain and to SAM-R/1, a resistant strain, from 2 months old. Effects of KMK on learning performance were evaluated in 5 and 10 month old SAM using step through and step down type passive avoidance tests and shuttle box and lever press type conditioned avoidance tests. At 5 months old KMK increased the retention rate in the step through test and decreased the number of errors in the step down test in SAM-P/8, though KMK had no effects in conditioned avoidance tests. KMK had no effects in any tests in SAM-R/1. At 10 months old, the decrease in the number of errors in the step down test and increase of the rate of the conditioned avoidance response in the shuttle box test were observed in SAM-P/8 treated with KMK. These results suggest that chronic administration of KMK can improve learning performance in the senescence model.

Aging↗
PubMedDate not supplied

Immunohistochemical studies of age-associated amyloid deposition in the joint of senescence-accelerated mouse (SAM).

The senescence-accelerated mouse (SAM) is a murine model of accelerated senescence and consists of the senescence-accelerated prone mouse (SAM-P) and senescence-accelerated resistant mouse (SAM-R), the latter of which shows normal aging characteristics. SAM shows a high incidence of age-associated microscopic amyloid deposition in synovial joints and intervertebral discs and the lesion is histologically quite similar to that of humans. The amyloid fibril protein of these mice is well characterized as a murine systemic senile amyloid (ASSAM). Twenty SAM-P and three SAM-R mice were used for this immunohistological study. Synovial joints and intervertebral discs were stained by immunoperoxidase method (PAP) using anti-ASSAM and anti-mouse AA antibodies and compared with birefringence in a Congo-red-stained section. Positive staining was observed in annulus fibrosus of the intervertebral discs, blood vessels, synovia, and on the surfaces of the meniscus and articular cartilage, exactly at the same site where green birefringence in Congo-red staining was observed. Both ASSAM and AA existed in the articular structures of SAM and the incidence of AA was significantly correlated with systemic signs of inflammation at autopsy. Among blood vessels, synovium and articular cartilage, there was no one tissue where amyloid deposited earlier than others. It was postulated that amyloid is transported via synovial fluid as its fibrillar form or as a precursor and that it deposits on the surface of articular cartilage.

Aging↗
PubMed1990

Influences of inhaled tobacco smoke on the senescence accelerated mouse (SAM).

We studied the influences of inhaled tobacco smoke on lung structure, biochemical changes in bronchoalveolar lavage (BAL) fluid, and glutathione (GSH) content of the lung in the senescence accelerated mouse (SAM), using 30 female SAM-P/8 as the "senescence-prone series", compared with SAM-R/1 as the "senescence-resistant series". At 18 wks of age, half of each series were housed in Hamburg II machines and exposed to an atmosphere of tobacco smoke for 5 wks, 10 min a day, 5 days a wk. At 24 wks of age, all of the animals were sacrificed. Blood, lung, liver, kidney and eyes were removed and the contents of GSH and thiol group (-SH) were measured (n = 5). We also performed BAL, to determine its total protein, albumin, and fibronectin contents, and elastase-like activity, elastase inhibitory capacity (EIC), and trypsin inhibitory capacity (TIC) (n = 5). Histological changes of the lungs from non-lavaged animals were also examined by light microscopy (n = 5). In SAM-P/8 not exposed to tobacco smoke, the mean linear intercept was longer than that in SAM-R/1. The exposure of SAM-P/8 to tobacco smoke caused increases in its lung weight and the ratio of albumin to total protein in BAL fluid, a decrease in the EIC/TIC ratio in BAL fluid, and a decrease in the GSH content and the GSH/-SH ratio of the lung, compared with those not exposed. We also observed focal infiltration of macrophages into alveoli with hyaline membrane and thickened alveolar wall in SAM-P/8 with tobacco exposure.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗
PubMed1989

[Genesis of systolic anterior motion (SAM) of the mitral valve in patients with aortic regurgitation].

This study was performed to evaluate the incidence and genesis of systolic anterior motion (SAM) of the mitral valve apparatus in patients with aortic regurgitation (AR). The study population consisted of 44 patients with non-rheumatic AR, without significant aortic stenosis or mitral regurgitation. The presence and location of SAM in the short-axis view were determined by M-mode echocardiography guided by two-dimensional echocardiography. The extent and direction of the regurgitant jet were decided by pulsed or two-dimensional Doppler echocardiography. SAM was observed in 21 (48%) of the 44 patients, and it was more frequently observed in patients with an etiology of aortic valve prolapse or annuloaortic ectasia than in those of other etiology (10/14 vs 10/30; p less than 0.05). Twenty-eight patients whose regurgitant jet was directed posteriorly and impinged on the mitral valve apparatus had a significantly higher incidence of SAM than did the other 16 patients (18/28 vs 3/16; p less than 0.01). In eight of 10 patients in whom the direction of the regurgitant jet could be precisely observed by two-dimensional Doppler echocardiography. SAM was observed at the place where a regurgitant jet was directed along the anterior mitral valve in the short-axis view. M-mode measurements (LVDd, LVDs, %FS, LVDd-LVDs) of the patients with SAM had greater values than those of patients without SAM.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1986

[SAM sound studied by pulsed Doppler echocardiography].

The occurrence of a systolic sound in hypertrophic obstructive cardiomyopathy (HOCM) has been well known for more than 20 years. This was phonoechocardiographically regarded as the sound coincident with the abrupt halt of the systolic anterior movement (SAM) of the mitral valve echo, and it has been termed the SAM sound. A 58-year-old man with HOCM was admitted with right hemiplegia. He was found to have a SAM sound which waxed and waned in intensity, and at times moved earlier into systole. He was studied by cardiac catheterization, M-mode and two-dimensional Doppler echocardiography (pulsed, continuous wave and color flow Doppler methods). Asymmetric septal hypertrophy (interventricular septal thickness = 25 mm, left ventricular posterior wall thickness = 14 mm), as well as SAM and midsystolic aortic valve closure were demonstrated. The presence and intensity of the sound was not related to rhythm (normal sinus rhythm vs atrial flutter), heart rate, respiration, position, or inhalation of amyl nitrite. Two-dimensional Doppler echocardiography revealed the following: 1. In the left ventricular outflow tract just below the aortic valve, a systolic turbulent flow was always present. 2. In the left ventricular chamber near the apex, a systolic laminar flow was interrupted in those cycles where the SAM sound was present. Otherwise, in cycles lacking the SAM sound, laminar flow in this locality continued throughout systole (even shorter duration than normal). 3. In the left ventricular inflow tract, diastolic flow was unaffected by the presence of the sound. 4. No mitral regurgitation was observed using color flow Doppler echocardiography. In summary, a SAM sound appeared to be associated with sudden deceleration of blood flow from the apex to the mid left ventricle.

Cardiomyopathy, Hypertrophic↗
PubMed1988

The WAIS-SAM: a comprehensive administrative model of modified WAIS procedures.

The WAIS-SAM (Ste. Anne's Method) is a procedure designed to reduce standard WAIS administration time and is applicable in virtually all cases. In order to evaluate the usefulness of the WAIS-SAM, the WAIS records of 80 male hospitalized war veterans (aged 55 to 82) were rescored in accordance with the WAIS-SAM procedure. Results were evaluated by Resnick and Entin's (1971) three validation criteria. Correlation between the WAIS-SAM and standard WAIS FSIQ was significantly high (.997) and satisfied the first criterion. A high degree of agreement between WAIS-SAM and WAIS (95%) in the classification of subjects into IQ categories satisfied the third criterion. The second criterion, however, was not met due to meager, though significant, mean differences. Despite this, it was concluded that the overall clinical value of the WAIS-SAM was demonstrated.

Aged↗
PubMed1997

SPR Studies of the Nonspecific Adsorption Kinetics of Human IgG and BSA on Gold Surfaces Modified by Self-Assembled Monolayers (SAMs)

The nonspecific binding of human immunoglobulin G (hIgG) and bovine serum albumin (BSA) was studied on gold surfaces modified by self-assembled alkyl thiol monolayers (SAMs) with the following terminal groups: CH3, C6H4OH, COO-, NH2, OH, and oligoethylene oxide (OEO). The kinetics of hIgG and BSA adsorption and desorption were monitored in real time utilizing the surface plasmon resonance (SPR) technique with a flow cell. The surface concentration of hIgG molecules adsorbed on the SAMs decreased in the order: CH3 > C6H5OH > COO- > NH2 > OH > OEO SAM surfaces. Binding of BSA to the SAM surfaces decreased in the order: C6H5OH > CH3 > COO- > NH2 > OH > OEO. The results show that on the OEO SAM, the surface concentration of these proteins was less than 0.5 ng/cm2 (the detection limit of our SPR device) and approximately 10(3) times less than that on the hydrophobic CH3-terminated SAM surfaces. The kinetics of the binding curves for the adsorption of the proteins are described in terms of multiple states of adsorbed proteins that involve multipoint hydrophobic, electrostatic, and hydrogen bond interactions for the different surfaces and protein lateral interactions caused by the unfolding of adsorbed proteins.

Journal Article↗
PubMed1999

Genetic typing of the senescence-accelerated mouse (SAM) strains with microsatellite markers.

The Senescence-Accelerated Mouse (SAM) strains constitute a murine model of accelerated senescence originating from the ancestral AKR/J strains and consist of nine senescence-prone (SAMP) strains and four senescence-resistant (SAMR) strains. The chromosomes (Chrs) of the SAM strains were typed with 581 microsatellite markers amplified by PCR, and the fundamental genetic information of the SAM strains was obtained. One-third of the examined markers displayed polymorphism among the strains, and only two alleles were detected in almost all loci among the SAM and AKR/J strains. However, in 12 loci (5.6% of total 215 polymorphic markers), the third allele was detected among the SAM strains. The genetic typing and developmental history suggested that the SAM strains were related inbred strains developed by the accidental crossing between the AKR/J strain and other unknown strain(s). Comparison of the distribution of the loci in the SAMP and the SAMR series revealed notable differences in the four regions on Chrs 4, 14, 16, and 17. This indicated that some of these chromosomal sites might contain the genes responsible for accelerated senescence in the SAMP series.

Aging↗
PubMed1991

Age-related alteration of brain gangliosides in senescence-accelerated mouse (SAM)-P/8.

The senescence-accelerated mouse (SAM)-P/8 was examined with respect to changes in the content and composition of brain gangliosides during aging from juvenile to senescence. The gangliosides were compared with those of control mice, senescence-accelerated resistant mouse (SAM)-R/1. The ganglioside contents in the whole brains of SAM-P/8 and -R/1 were at almost constant level from 0.5 to 6 months, but decreased thereafter until senescence to about 80% of the levels reached at the younger ages. Upon aging, the ganglioside compositions changed with an increase of GM1, and decreases of GD1a, GD1b and GT1b in both strains (GT1b greater than GD1a greater than GD1b). A minor component, GM3 was two to four fold higher in the molecular distributions of the whole brain gangliosides of SAM-P/8 than those of -R/1 at any age examined throughout the life span. The regional gangliosides in olfactory bulb, cerebral cortex, hippocampus, hypothalamus, cerebellum, corpora quadrigemina region, brain stem and medulla oblongata were compared between the two strains at the age of three months. The ganglioside contents in the brain stem and medulla oblongata were lower in SAM-P/8 than -R/1, but there was no significant difference between the two strains in the other regions. As a minor component, GM3 was found to occur in a higher concentration in SAM-P/8 than -R/1 in all brain regions examined, except in the olfactory bulb where GM3 was detected as a major component with no difference in the distribution level between the two strains.

Aging↗
PubMed1989

Modification of strain-specific femoral bone density by bone marrow chimerism in mice: a study on the spontaneously osteoporotic mouse (SAM-P/6).

The role of marrow-derived cells in determining strain differences in femoral bone density in mice was investigated by inducing marrow chimerism in a newly developed, osteoporotic strain of mouse: SAM-P/6. As a normative study prior to the chimeric experiment, bone density of F1 hybrids between SAM-P/6 and SAM-P/2 (strain with a high bone density) was assessed. Microdensitometrically, the F1(P2P6F1) exhibited a significantly higher bone density than did the SAM-P/6. P2P6F1 marrow cells, injected into SAM-P/6 neonates, increased the bone density at age 60 days while the syngeneic cells were without effect. The successful induction and maintenance of chimerism was confirmed by flow cytometry in which a donor-specific H-2K haplotype was used as the marker. This study shows that, at least in certain combinations of strains of mice, strain-specific bone density can be modified by bone marrow chimerism. Also, it suggests that the low bone density observed in the SAM-P/6 might reflect functional characteristics of the marrow-derived cells.

Animals↗
PubMedDate not supplied

SAM-systolic anterior motion of the anterior mitral valve leaflet post-surgical mitral valve repair.

Systolic anterior motion (SAM) is a postoperative complication experienced by patients undergoing mitral valve repair. The incidence of SAM after mitral valve repair ranges from 5 to 10%. Early recognition of the signs and symptoms of SAM is imperative to the management of these patients. This article presents the pathophysiology of mitral valve dysfunction to give the practitioner a clear understanding of the dynamics of SAM. This article's main focus is the detection and management of SAM and the most current treatment modalities. A case study is used to illustrate the complex management necessary for the patient with SAM.

Aged↗
PubMed2005

Solution structure of the Vts1 SAM domain in the presence of RNA.

The yeast Vts1 SAM (sterile alpha motif) domain is a member of a new class of SAM domains that specifically bind RNA. To elucidate the structural basis for RNA binding, the solution structure of the Vts1 SAM domain, in the presence of a specific target RNA, has been solved by multidimensional heteronuclear NMR spectroscopy. The Vts1 SAM domain retains the "core" five-helix-bundle architecture of traditional SAM domains, but has additional short helices at N and C termini, comprising a small substructure that caps the core helices. The RNA-binding surface of Vts1, determined by chemical shift perturbation, maps near the ends of three of the core helices, in agreement with mutational data and the electrostatic properties of the molecule. These results provide a structural basis for the versatility of the SAM domain in protein and RNA-recognition.

Amino Acid Motifs↗
PubMed2001

COMT-dependent protection of dopaminergic neurons by methionine, dimethionine and S-adenosylmethionine (SAM) against L-dopa toxicity in vitro.

L-dopa may be toxic to dopamine neurons, possibly due to catechol-autoxidation. Catechols are O-methylated by catechol-O-methyltransferase (COMT) in a SAM consuming reaction, preventing the initiation of catechol autoxidation. We hypothesized that SAM or SAM-precursors ameliorate L-dopa neurotoxicity, in a COMT-dependent fashion. We tested this hypothesis in primary mesencephalic cultures by adding 200 microM L-dopa with 2 mM methionine or 1 mM dimethionine or 0.5 mM SAM with or without 0.2 microM of the COMT-inhibitor 2', 5'-dinitrocatechol (OR 486). L-dopa was found to be neurotoxic as the surviving neurons had fewer and shorter processes. Methionine, dimethionine and SAM all protected DA neurons against damaged induced by L-dopa. The COMT inhibitor dinitrocatechol (DNC) completely abolished the protective effect against L-dopa toxicity. We conclude that supplementation with methionine, dimethionine or SAM ameliorates L-dopa neurotoxicity to dopamine neurons, while inhibition of COMT may aggravate or unmask L-dopa neurotoxicity.

Animals↗
PubMed2000

Farnesyl-L-cysteine analogs block SAM-induced Parkinson's disease-like symptoms in rats.

Injection of the endogenous methyl donor, S-adenosyl methionine (SAM), into rat brain induces Parkinson's disease (PD)-like symptoms possibly by stimulating deleterious protein methylation. Gel-filtration chromatography of rat brain extracts treated with [3H-methyl]-SAM revealed the presence of radioactive peaks with apparent molecular weights of about 5 kDa. Treatment with guanidine HCl altered the elution volumes of the labeled peaks. Lyophilized peak fractions released volatile 3H-methanol on incubation with NaOH, indicating the presence of carboxyl methyl esters. Because prenylated proteins are avid methyl acceptors at the terminal carboxylic acid groups, 1 micromol S-farnesylcysteine (FC) analogs blocked the SAM-induced tremors in the experimental rats. FC analogs did not only reverse the associated rigidity, abnormal posture, and hypokinesia, but stimulated hyperactivity in the animals. This amphetamine-like effect was monitored for 20 min in an animal activity monitor and movement times between 400 +/- 100 and 560 +/- 125 s covering distances between 78 +/- 29 to 125 +/- 35 m were recorded for rats treated with FC analogs with or without SAM. Control animals moved only for 60 +/- 13 s covering about 6 +/- 1 m, indicating a 7-9-fold and 13-21-fold increase in duration of movement and distance covered, respectively. N-Acetyl-S-farnesylcysteine (AFC) potentiated amphetamine-induced ipsiversive rotation of 6-hydroxydopamine-lesioned rats from 390 +/- 130 to 830 +/- 110, with AFC alone having no significant effect on net rotation compared to controls. These data indicate that intracerebroventricular injection of SAM may induce PD symptoms by interfering with the methylation/demethylation homeostasis of prenylated proteins that function in the dopaminergic and other signaling pathways, and that the FC analogs may counteract the SAM effects by acting synergistically on events subsequent to neurotransmitter release.

Amphetamine↗
PubMed2006

Orientation of 6-mercaptopurine SAMs at the silver electrode as studied by Raman mapping and in situ SERS.

Self-assembled monolayers (SAMs) of 6-mercaptopurine (6MP) on a silver electrode in acid and alkaline media were investigated by a combination protocol of the SERS technique with Raman mapping, and it was found that the adsorption mode of 6MP SAMs changed with the pH value of the environment. Quantum calculations for the vibrational mode were performed by the BLYP/6-31G method. 6MP was adsorbed on the silver electrode with a tilted orientation via S, N1, and N7 atoms in acid medium, while the SAMs adopted head-on adsorption modes with the S atom and the N1 atom anchoring the silver surface in alkaline medium. However, 6MP SAMs turned to the same upright orientation on the electrode through the S and N7 atoms when either acid or basic solution was removed. Stability of 6MP SAMs was observed by in situ SERS spectroelectrochemical measurements. The results reveal that the desorption potentials of 6MP SAMs formed under acid and alkaline conditions from the Ag electrode were at ca. -1.3 V and -1.6 V vs SCE, respectively.

Adsorption↗
PubMed2006

Loosely packed hydroxyl-terminated SAMs on gold.

We report the preparation of loosely packed hydroxyl-terminated self-assembled monolayers (SAMs) on gold by the adsorption of bis(11,11'-dithioundecyl)perfluoroheptanoate and base-mediated cleavage of the fluorocarbon terminal group. As shown through complementary characterization methods, the partially fluorinated SAM exhibits a structure in which the outer surface contains mostly -CF(3) groups, the fluorocarbon groups are slightly canted on average, and the hydrocarbon chains underneath are in a fluidlike state. Upon cleavage of the fluorocarbon group, the hydroxyl-terminated alkyl chains relax into an increasingly canted, fluidlike state. The resulting monolayer packing exposes both methylene and hydroxyl functionalities, yielding an intermediate surface energy (theta(a)(H(2)O) approximately 68 degrees ). As compared to a densely packed hydroxyl-terminated SAM prepared from bis(11-hydroxyundecyl)disulfide, the cleaved films are thinner because of the greater average chain cant and exhibit a approximately 50% higher capacitance and a factor of 5 lower charge-transfer resistance. The addition of THF to the electrolyte solution as a cosolvent intercalates into the loosely packed SAM to double the charge-transfer resistance and increase the capacitance by approximately 20% but does not affect the capacitance of the densely packed SAM. The loosely packed SAM is also more easily exchanged upon exposure to a solution of n-docosanethiol.

Journal Article↗
PubMed2006

Shape-specific recognition in the structure of the Vts1p SAM domain with RNA.

Although the abundant sterile alpha motif (SAM) domain was originally classified as a protein-protein interaction domain, it has recently been shown that certain SAM domains have the ability to bind RNA, defining a new type of post-transcriptional gene regulator. To further understand the function of SAM-RNA recognition, we determined the solution structures of the SAM domain of the Saccharomyces cerevisiae Vts1p (Vts1p-SAM) and the Smaug response element (SRE) stem-loop RNA as a complex and in isolation. The structures show that Vts1p-SAM recognizes predominantly the shape of the SRE rather than its sequence, with the exception of a G located at the tip of the pentaloop. Using microarray gene profiling, we identified several genes in S. cerevisiae that seem to be regulated by Vts1p and contain one or more copies of the SRE.

Amino Acid Sequence↗
PubMed2006

Sequence-specific recognition of RNA hairpins by the SAM domain of Vts1p.

The SAM domain of the Saccharomyces cerevisiae post-transcriptional regulator Vts1p epitomizes a subfamily of SAM domains conserved from yeast to humans that function as sequence-specific RNA-binding domains. Here we report the 2.0-A X-ray structure of the Vts1p SAM domain bound to a high-affinity RNA ligand. Specificity of RNA binding arises from the association of a guanosine loop base with a shallow pocket on the SAM domain and from multiple SAM domain contacts to the unique backbone structure of the loop, defined in part by a nonplanar base pair within the loop. We have validated NNF1 as an endogenous target of Vts1p among 79 transcripts that copurify with Vts1p. Bioinformatic analysis of these mRNAs demonstrates that the RNA-binding specificity of Vts1p in vivo is probably more stringent than that of the isolated SAM domain in vitro.

Base Pairing↗