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排序方式: 共有287条查询结果,搜索用时 15 毫秒
1.
Jaime Guevara-Aguirre Arlan L Rosenbloom Marco Guevara-Aguirre Kemal Yariz Jeanette Saavedra Lisa Baumbach Jonathan Shuster 《Growth hormone & IGF research》2007,17(3):261-264
CONTEXT & OBJECTIVE: The Ecuadorian GH receptor deficiency (GHRD)/Laron syndrome population is the only large cohort with a single GHR mutation (E180 splice), permitting identification of numerous carrier and noncarrier first-degree relatives, to ascertain effects of heterozygosity on GH-dependent IGF-I and IGFBP-3 concentrations and on growth. DESIGN: First-degree relatives (n=212) of GHRD patients had specimens taken for IGF-I, IGFBP-3, and GHR genotyping. Normal statured (n=40) and short statured (n=40) unrelated controls had measurement of IGF-I, IGFBP-3, and stature. RESULTS: There were no significant differences between heterozygous and homozygous normal relatives in IGF-I or IGFBP-3 standard deviation scores (SDS). Heterozygous relatives had lower mean height SDS than did homozygous normals, but with extensive overlap between genotype groups in both child and adult relatives. Height SDS in general did not relate to IGF-I or IGFBP-3 concentrations. CONCLUSIONS: GH-dependent IGF-I and IGFBP-3 secretion is not affected by heterozygosity for the E180 splice mutation that causes GHRD/Laron syndrome in the Ecuadorian population. Heterozygosity is associated with reduction in mean statural SDS, but this is not sufficient to be clinically important and not mediated through measurable differences in circulating IGF-I or IGFBP-3 related to genotype. 相似文献
2.
Dao Yin Xie Stefan Hassenstein Martin Oberhoff Hartmut Hanke Andreas Baumbach Kristian Hohla Karl Konstantin Haase Karl Rüdiger Karsch 《Lasers in surgery and medicine》1993,13(6):618-624
A modified exeimer laser energy delivery system was used to irradiate 100 segments of normal and fibrous aorta in vitro. The laser beam was scanned into 8 fiber bundles consisting of 50 fibers each resulting in a reduction of the applied pulse energy. The total repetition rate was increased to 150 Hz in order to keep the repetition rate per fiber bundle close to 20 Hz and to minimize thermal injury. The results demonstrate that effective ablation (etch rate per 8 pulses > 2.0 μm) occurred at an energy fluency of 50 mJ/mm2 in both normal and fibrous aorta. Tissue damage (carbonization, tissue separation, fissures, cracks, and vacuolization) was in a range of 100 ± 28 to 152 ± 30 μm for normal aorta and in a range of 57 ± 35 to 110 ± 39 μm for fibrous aorta. We conclude that effective ablation of normal and fibrous human aorta can be achieved by the application of smooth excimer laser coronary angioplasty. This improvement of excimer laser technology may result in a reduction of shock wave- and cavitation-induced damage leading to a reduction of tissue injury. However, this awaits further in vitro and in vivo confirmation. © 1993 Wiley-Liss, Inc. 相似文献
3.
Differentiation of Streptococcus uberis from Streptococcus parauberis by polymerase chain reaction and restriction fragment length polymorphism analysis of 16S ribosomal DNA.
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B M Jayarao J J Dor Jr G A Baumbach K R Matthews S P Oliver 《Journal of clinical microbiology》1991,29(12):2774-2778
Streptococcus uberis type II has been proposed recently as a separate species designated Streptococcus parauberis (A. M. Williams and M. D. Collins, J. Appl. Bacteriol. 68:485-490, 1990). Differentiation of S. parauberis from S. uberis has been possible only by DNA-DNA hybridization or 16S rRNA sequencing, since the biochemical and serological characteristics of the two species are indistinguishable. A simple and reliable technique was developed for differentiating S. parauberis (S. uberis type II [ATCC 13386]) from S. uberis (S. uberis type I [ATCC 9927, ATCC 13387, and ATCC 27958]) by restriction fragment length polymorphism (RFLP) analysis of 1.4-kb 16S ribosomal DNA (rDNA). Oligonucleotide primers complementary to 16S rRNA genes were used to amplify 16S ribosomal gene fragments from genomic DNA by polymerase chain reaction. The 1.4-kb 16S rDNA fragment was digested with ScaI, NspI, DdeI, and AvaII restriction endonucleases. Restriction fragments produced by all four restriction endonucleases were characteristic for each species. RFLP analysis of 16S rDNA from 24 "S. uberis" isolates obtained from mammary secretions of dairy cows indicated that all 24 isolates were indeed S. uberis. 相似文献
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Christian T. Wolowiec Noravee Kanchanavatee Kevin Huang Sheng Ran Alexander J. Breindel Naveen Pouse Kalyan Sasmal Ryan E. Baumbach Greta Chappell Peter S. Riseborough M. Brian Maple 《Proceedings of the National Academy of Sciences of the United States of America》2021,118(20)
Electrical resistivity measurements were performed on single crystals of URu2–xOsxSi2 up to x = 0.28 under hydrostatic pressure up to P = 2 GPa. As the Os concentration, x, is increased, 1) the lattice expands, creating an effective negative chemical pressure Pch(x); 2) the hidden-order (HO) phase is enhanced and the system is driven toward a large-moment antiferromagnetic (LMAFM) phase; and 3) less external pressure Pc is required to induce the HOLMAFM phase transition. We compare the behavior of the T(x, P) phase boundary reported here for the URu2-xOsxSi2 system with previous reports of enhanced HO in URu2Si2 upon tuning with P or similarly in URu2–xFexSi2 upon tuning with positive Pch(x). It is noteworthy that pressure, Fe substitution, and Os substitution are the only known perturbations that enhance the HO phase and induce the first-order transition to the LMAFM phase in URu2Si2. We present a scenario in which the application of pressure or the isoelectronic substitution of Fe and Os ions for Ru results in an increase in the hybridization of the U-5f-electron and transition metal d-electron states which leads to electronic instability in the paramagnetic phase and the concurrent formation of HO (and LMAFM) in URu2Si2. Calculations in the tight-binding approximation are included to determine the strength of hybridization between the U-5f-electron states and the d-electron states of Ru and its isoelectronic Fe and Os substituents in URu2Si2.The heavy-fermion superconducting compound is known for its second-order phase transition into the so-called “hidden-order” (HO) phase at a transition temperature 17.5 K. Extensive investigation of the phase space in proximity to the HO phase transition has provided a detailed picture of the electronic and magnetic structure of this unique phase (1–42). However, more than three decades after the initial characterization of (1–3), the order parameter for the HO phase is still unidentified.Most perturbations to the compound have the effect of suppressing HO. The application of an external magnetic field () suppresses the HO phase (41, 43) and many of the chemical substitutions () at the U, Ru, or Si sites that have been explored significantly reduce , even at modest levels of substituent concentration (44–52). At present, only three perturbations are known to consistently enhance the HO phase in : 1) external pressure , 2) isoelectronic substitution of Fe ions for Ru, and 3) isoelectronic substitution of Os ions for Ru. Upon applying pressure , the HO phase in pure is enhanced (6) and the system is driven toward a large-moment antiferromagnetic (LMAFM) phase (53). The HOLMAFM phase transition is identified indirectly by a characteristic “kink” at a critical pressure 1.5 GPa in the () phase boundary (18, 53, 54) and also directly by neutron diffraction experiments, which reveal an increase in the magnetic moment from /U in the HO phase to /U in the LMAFM phase (13, 55, 56).Recent reports indicate that the isoelectronic substitution of Fe ions for Ru in replicates the behavior in (57–59). An increase in in enhances the HO phase and drives the system toward the HOLMAFM phase transition at a critical Fe concentration 0.15 (58, 60). The decrease in the volume of the unit cell due to substitution of smaller Fe ions for Ru may be interpreted as a chemical pressure, , where the Fe concentration can be converted to () (57, 59). In addition, the induced HOLMAFM phase transition in occurs at combinations of and that consistently obey the additive relationship: + 1.5 GPa (57, 59). These results have led to the suggestion that is equivalent to in affecting the HO and LMAFM phases (58, 59).Reports of the isoelectronic substitution of larger Os ions for Ru have shown that an increase in in 1) expands the volume of the unit cell, thus creating an effective negative chemical pressure (0); 2) enhances the HO phase; and 3) drives the system toward a similar HOLMAFM phase transition at a critical Os concentration of 0.065 (60–62). These results are contrary to the expectation that a negative would lead to a suppression of HO and complicate the view of chemical pressure as a mechanism affecting the evolution of phases in .In this paper, we report on the behavior of the (, ) boundary for the system based on measurements of single crystals of as a function of Os concentration and applied pressure . The (, ) phase boundary observed here for the system (57–59) is compared to that of the system and also with the behavior of in pure . As an explanation for the enhancement of HO toward the HOLMAFM phase transition, we suggest a scenario in which each of the perturbations of Os substitution, Fe substitution, and pressure favors delocalization of the 5 electrons and increases the hybridization of the uranium 5-electron and transition metal (Fe, Ru, Os) -electron states. To avoid an ad hoc explanation of the effect of increasing the Os concentration in , compared to the effects of pressure and Fe substitution, we explain how pressure , Fe substitution, and Os substitution are three perturbative routes to enhancement of the U-5- and -electron hybridization. The importance of the 5- and -electron hybridization to the emergence of HO/LMAFM is presented in the context of the Fermi surface (FS) instability that leads to a reconstruction and partial gapping of the FS during the transition from the paramagnetic (PM) phase to the HO and LMAFM phases (2, 6, 20, 22, 24–26, 37, 38, 63).In an effort to further understand the effect of isoelectronic substitution on the 5- and -electron hybridization, calculations in the tight-binding approximation were made for compounds from the series U ( = Fe, Ru, and Os). The calculations indicate that the degree of hybridization is largely dependent on the magnitude of the difference between the binding energy of the localized U-5 electrons and that of the transition metal electrons. 相似文献
7.
J. Seidel E. Färber R. Baumbach W. Cordruwisch U. Böhmler B. Feyerabend S. Faiss 《International journal of colorectal disease》2016,31(3):603-611
Purpose
Endoscopic resection is a widely used technique for treatment of large colorectal adenomas, but few data are available including only lesions larger than ≥2 cm. The aim of this study is to evaluate the complication and recurrence rate after endoscopic resection of high-risk colorectal adenomas ≥3 cm in size.Methods
Retrospective analysis of a prospectively maintained database of patients undergoing polypectomy of large colorectal polyps of ≥3 cm.Results
In 341 patients, 360 colorectal adenomas with a mean size of 3.9 cm were resected endoscopically. In 25 patients, a complication including 22 delayed bleedings (6.5 %) and three perforations (0.9 %) occurred. Single-variate analysis showed an increasing risk of complications for larger adenomas (3.9 vs. 4.6 cm; p?≤?0.05). Two hundred twelve patients with 224 adenomas had undergone at least one documented follow-up endoscopy with a medium follow-up period of 16 months. In 95 resected lesions (42.4 %), a residual adenoma occurred in the first follow-up colonoscopy (n?=?88, 92.6 %) or a recurrent adenoma occurred after at least one negative follow-up colonoscopy (n?=?7, 7.4 %). In multivariate analysis, risk factors were lesion size, sessile growth pattern, and the performing endoscopist. The complication and recurrence rate correlated inversely between endoscopists.Conclusions
The present study is the largest study showing complication and recurrence rates after colorectal polypectomy of advanced colorectal adenomas of ≥3 cm in size. Polyp size was identified as the most important risk factor for complications. For the first time, this study shows that the complication rate after colorectal polypectomy of large adenomas is correlated inversely with the residual and/or recurrence rate.8.
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We examined effects of hyperhomocysteinemia on structure and mechanics of cerebral arterioles. We measured plasma total homocysteine (tHcy) and pressure, diameter, and cross-sectional area of the vessel wall in maximally dilated cerebral arterioles in heterozygous cystathionine beta-synthase-deficient (CBS(+/-)) mice and wild-type (CBS(+/+)) littermates that were provided with drinking water that was unsupplemented (control diet) or supplemented with 0.5% L-methionine (high-methionine diet). Plasma tHcy was 5.0+/-1.1 micro mol/L in CBS(+/+) mice and 8.3+/-0.9 micro mol/L in CBS(+/-) mice (P<0.05 versus CBS(+/+) mice) fed the control diet. Plasma tHcy was 17.2+/-4.6 micro mol/L in CBS(+/+) mice and 21.2+/-3.9 micro mol/L in CBS(+/-) mice (P<0.05) fed the high-methionine diet. Cross-sectional area of the vessel wall was significantly increased in CBS(+/-) (437+/-22 micro m(2)) mice fed control diet and CBS(+/+) (442+/-36 micro m(2)) and CBS(+/-) (471+/-46 micro m(2)) mice fed high-methionine diet relative to CBS(+/+) (324+/-18 micro m(2)) mice fed control diet (P<0.05). During maximal dilatation, the stress-strain curves in cerebral arterioles of CBS(+/-) mice on control diet and CBS(+/+) and CBS(+/-) mice on high-methionine diet were shifted to the right of the curve in cerebral arterioles of CBS(+/+) mice on control diet, an indication that distensibility of cerebral arterioles was increased in mice with elevated levels of plasma tHcy. Thus, hyperhomocysteinemia in mice was associated with hypertrophy and an increase in distensibility of cerebral arterioles. These findings suggest that hyperhomocysteinemia promotes cerebral vascular hypertrophy and altered cerebral vascular mechanics, both of which may contribute to the increased incidence of stroke associated with hyperhomocysteinemia. 相似文献