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991.
Phillips NJ Schilling B McLendon MK Apicella MA Gibson BW 《Infection and immunity》2004,72(9):5340-5348
We have investigated the lipid A of Francisella tularensis subsp. holarctica strain 1547-57, a type B strain, by using matrix-assisted laser desorption ionization-time-of-flight mass spectrometry, nanoelectrospray quadrupole ion-trap mass spectrometry, and chemical methods. In accordance with the previously published structures of the lipid A from F. tularensis live vaccine strain (LVS) (ATCC 29684) (E. Vinogradov et al., Eur. J. Biochem. 269:6112-6118, 2002), all of the major lipid A forms from strain 1547-57 were tetraacylated. As in the LVS strain, the major fatty acids detected in the F. tularensis 1547-57 lipid A sample included 3-hydroxyoctadecanoic acid, 3-hydroxyhexadecanoic acid, hexadecanoic acid, and tetradecanoic acid. However, several of the lipid A components present in strain 1547-57 were of higher molecular weight than the previously published structures. A major component with an M(r) of 1,666 was found to contain three C(18:0)(3-OH) fatty acids, one C(16:0) fatty acid, one phosphate group, and one 161-Da moiety. This 161-Da moiety could be removed from the lipid A by treatment with aqueous hydrofluoric acid and was identified as galactosamine following peracetylation and analysis by gas chromatography-mass spectrometry. Detailed investigations of the M(r)-1,666 species by ion-trap mass spectrometry with multiple stages of fragmentation suggested that the galactosamine-1-phosphate was linked to the reducing terminus of the lipid A. Similar to the modification of lipid A with arabinosamine, lipopolysaccharide species from F. tularensis containing a phosphate-linked galactosamine could potentially influence its intracellular survival by conferring resistance to antimicrobial peptides. 相似文献
992.
Performance of the TechLab C. DIFF CHEK-60 enzyme immunoassay (EIA) in combination with the C. difficile Tox A/B II EIA kit, the Triage C. difficile panel immunoassay, and a cytotoxin assay for diagnosis of Clostridium difficile-associated diarrhea 下载免费PDF全文
We compared a recently marketed enzyme immunoassay for glutamate dehydrogenase (GDH), TechLab's C. DIFF CHEK-60 (TL-GDH), in combination with the C. difficile Tox A/B II enzyme immunoassay (Tox-A/B) with (i) the Triage C. difficile test, which detects both GDH (TR-GDH) and toxin A (TR-Tox-A); (ii) an in-house cytotoxin assay (C-Tox); and (iii) stool cultures for C. difficile. All C. difficile isolates were tested for the presence of the toxin genes by PCR. If a toxin gene-positive strain of Clostridium difficile was recovered and a toxin was detected by any method, the result was considered to be truly positive. Eighty-seven of 93 and 79 of 93 C. difficile culture-positive samples were also TL-GDH and TR-GDH positive, respectively. No test was able to detect toxin in all samples with true-positive results. Tox-A/B and TR-Tox-A in combination with the GDH detection tests and C-Tox were able to identify 52 and 50 samples with true-positive results. Tox-A/B and TR-Tox-A would have missed 15 and 31% of cases of C. difficile-associated diarrhea, respectively, if used alone. 相似文献
993.
Microbial infections,immunomodulation, and drugs of abuse 总被引:12,自引:0,他引:12
The use of recreational drugs of abuse has generated serious health concerns. There is a long-recognized relationship between addictive drugs and increased levels of infections. Studies of the mechanisms of actions of these drugs became more urgent with the advent of AIDS and its correlation with abused substances. The nature and mechanisms of immunomodulation by marijuana, opiates, cocaine, nicotine, and alcohol are described in this review. Recent studies of the effects of opiates or marijuana on the immune system have demonstrated that they are receptor mediated, occurring both directly via specific receptors on immune cells and indirectly through similar receptors on cells of the nervous system. Findings are also discussed that demonstrate that cocaine and nicotine have similar immunomodulatory effects, which are also apparently receptor mediated. Finally, the nature and mechanisms of immunomodulation by alcohol are described. Although no specific alcohol receptors have been identified, it is widely recognized that alcohol enhances susceptibility to opportunistic microbes. The review covers recent studies of the effects of these drugs on immunity and on increased susceptibility to infectious diseases, including AIDS. 相似文献
994.
995.
McCrea M 《Journal of Athletic Training》2001,36(3):274-279
OBJECTIVE: The effects of concussion on mental status are often difficult to assess on routine clinical examination. I investigated the efficacy of standardized mental status testing on the sport sideline to detect abnormalities that result from concussion and provide an objective measure of postinjury cognitive recovery. DESIGN AND SETTING: All subjects underwent a standardized preseason baseline mental status evaluation. Standardized testing of injured and uninjured control subjects was repeated on the sideline immediately after concussion and 48 hours after injury. SUBJECTS: Sixty-three high school and collegiate football players with concussion and 55 uninjured control subjects were studied. MEASUREMENTS: The Standardized Assessment of Concussion (SAC) was administered to evaluate neurocognitive functioning and neurologic status. RESULTS: Immediately after concussion, injured subjects performed significantly below preinjury baseline and below uninjured controls on the SAC. Measurable deficits in orientation, concentration, and memory were evident immediately after concussion. A decline in SAC score at time of injury was 95% sensitive and 76% specific in accurately classifying injured and uninjured subjects on the sideline. Injured subjects demonstrated significant improvements in SAC score 48 hours after injury. CONCLUSIONS: Standardized mental status testing can be a valuable tool to assist the sports medicine clinician in detecting the immediate effects of concussion on mental status, tracking resolution of immediate postconcussive mental status abnormalities, and making more informed decisions on return to play after injury. 相似文献
996.
997.
John P. McCarthy Marcas M. Bamman Janice M. Yelle Adrian D. LeBlanc Roger M. Rowe Michael C. Greenisen Stuart M. C. Lee Elisabeth R. Spector Suzanne M. Fortney 《European journal of applied physiology》1997,76(1):32-40
Resistance exercise has been suggested to increase blood volume, increase the sensitivity of the carotid baroreceptor cardiac reflex response (BARO), and decrease leg compliance, all factors that are expected to improve orthostatic tolerance. To further test these hypotheses, cardiovascular responses to standing and to pre-syncopal limited lower body negative pressure (LBNP) were measured in two groups of sedentary men before and after a 12-week period of either exercise (n = 10) or no exercise (control, n = 9). Resistance exercise training consisted of nine isotonic exercises, four sets of each, 3 days per week, stressing all major muscle groups. After exercise training, leg muscle volumes increased (P?0.05) by 4–14%, lean body mass increased (P = 0.00) by 2.0 (0.5)?kg, leg compliance and BARO were not significantly altered, and the maximal LBNP tolerated without pre-syncope was not significantly different. Supine resting heart rate was reduced (P = 0.03) without attenuating the heart rate or blood pressure responses during the stand test or LBNP. Also, blood volume (125I and 51Cr) and red cell mass were increased (P?0.02) by 2.8% and 3.9%, respectively. These findings indicate that intense resistance exercise increases blood volume but does not consistently improve orthostatic tolerance. 相似文献
998.
Eye movements induced by lateral acceleration steps
Effect of visual context and acceleration levels
C. C. Gianna Michael A. Gresty Adolfo M. Bronstein 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》1997,114(1):124-129
Eye movement responses were obtained from six normal subjects exposed to randomly ordered rightwards/leftwards linear acceleration
steps of 0.05 g, 0.1 g or 0.24 g amplitude and 650 ms duration along the inter-aural axis. With the instruction to gaze passively into the darkness, compensatory nystagmus was evoked with slow-phase velocity sensitivity of 49° s−1
g
−1. When subjects viewed earth-fixed targets at 30 cm, 60 cm or 280 cm, eye movements at 130 ms from motion onset were proportional to acceleration and inversely proportional
to target distance, before the onset of visually guided eye movements. Our results show that a modulation with viewing distances
of the earliest human otolith-ocular reflexes occurs in the presence of pure linear acceleration. However, full compensation
was not attained for the nearer targets and higher accelerations.
Received: 31 January 1996 / Accepted: 30 September 1996 相似文献
999.
Kenneth S. Kendler Ellen E. Walters Kim R. Truett Andrew C. Heath Michael C. Neale Nicholas G. Martin Lindon J. Eaves 《Behavior genetics》1995,25(6):499-515
Self-report symptoms of anxiety are widely used in mental health and social science research as an index of current psychiatric
state. Previous twin studies have suggested that genetic factors account for a significant proportion of the variance in these
symptoms. To replicate and extend these findings, we examined self-report symtoms of panic-phobia and somatization in the
“Virginia 30,000” twin-family sample. Model fitting applied to 80 unique relationships in the twin-family pedigree produced
the following major results: (i) genetic effects were significant for both symptom factors, accounting for between 25 and
49% of the total variance, with the exception of symptoms of panic-phobia in females, where they accounted for 15–16% of the
variance; (ii) familial environmental effects were absent for symptoms of somatization, while for symptoms of panic-phobia
they accounted for a very small proportion of variance in males (≤1.2%) and a modest proportion in females (6–17%) (iii) spousal
correlations were present for both factors, ranging from +0.05 to +0.20; (iv) genetic factors which influenced symptoms were
generally the same in males and females, although their effect was greater in males; (v) heritability estimates were lower
in the population-based than in the volunteer sample; and (vi) when test-retest reliability was included in the model, results
suggest that genetic factors account for at least half of the stable variance for all symptom factors, except panic-phobia
in females. Our results support the validity of previous twin studies of self-report symptoms of anxiety and suggest that
genetic factors significantly influence these symptoms but familial-environmental factors play little or no etiologic role. 相似文献
1000.
Experimental Infection of Mongolian Gerbils with Wild-Type and Mutant Helicobacter pylori Strains 总被引:12,自引:0,他引:12 下载免费PDF全文
Hans-Peter Wirth Michael H. Beins Manqiao Yang Kyi T. Tham Martin J. Blaser 《Infection and immunity》1998,66(10):4856-4866
Experimental Helicobacter pylori infection was studied in Mongolian gerbils with fresh human isolates that carry or do not carry cagA (cagA-positive or cagA-negative, respectively), multiply passaged laboratory strains, wild-type strain G1.1, or isogenic ureA, cagA, or vacA mutants of G1.1. Animals were sacrificed 1 to 32 weeks after challenge, the stomach was removed from each animal for quantitative culture, urease test, and histologic testing, and blood was collected for antibody determinations. No colonization occurred after ≥20 in vitro passages of wild-type strain G1.1 or with the ureA mutant of G1.1. In contrast, infection occurred in animals challenged with wild-type G1.1 (99 of 101 animals) or the cagA (25 of 25) or vacA (25 of 29) mutant of G1.1. Infection with G1.1 persisted for at least 8 months. All 15 animals challenged with any of three fresh human cagA-positive isolates became infected, in contrast to only 6 (23%) of 26 animals challenged with one of four fresh human cagA-negative isolates (P < 0.001). Similar to infection in humans, H. pylori colonization of gerbils induced gastric inflammation and a systemic antibody response to H. pylori antigens. These data confirm the utility of gerbils as an animal model of H. pylori infection and indicate the importance of bacterial strain characteristics for successful infection. 相似文献