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T Horn

Publications and source records attributed to T Horn.

At least 19 recordsLinked to original sources
PubMed2006

Determination of the pion charge form factor at Q2=1.60 and 2.45 (GeV/c)2.

The 1H(e,e'pi+)n cross section was measured at four-momentum transfers of Q2=1.60 and 2.45 GeV2 at an invariant mass of the photon nucleon system of W=2.22 GeV. The charged pion form factor (F(pi)) was extracted from the data by comparing the separated longitudinal pion electroproduction cross section to a Regge model prediction in which F(pi) is a free parameter. The results indicate that the pion form factor deviates from the charge-radius constrained monopole form at these values of Q2 by one sigma, but is still far from its perturbative quantum chromodynamics prediction.

Journal Article↗
PubMed2005

Q2 dependence of the neutron spin structure function g2(n) at low Q2.

We present the first measurement of the Q2 dependence of the neutron spin structure function g2(n) at five kinematic points covering 0.57 (GeV/c)2 < or = Q2 < or = 1.34 (GeV/c)2 at x approximately = 0.2. Though the naive quark-parton model predicts g2 = 0, nonzero values occur in more realistic models of the nucleon which include quark-gluon correlations, finite quark masses, or orbital angular momentum. When scattering from a noninteracting quark, g2(n) can be predicted using next-to-leading order fits to world data for g1(n). Deviations from this prediction provide an opportunity to examine QCD dynamics in nucleon structure. Our results show a positive deviation from this prediction at lower Q2, indicating that contributions such as quark-gluon interactions may be important. Precision data obtained for g1(n) are consistent with next-to-leading order fits to world data.

Journal Article↗
PubMed2005

Strange-quark contributions to parity-violating asymmetries in the forward g0 electron-proton scattering experiment.

We have measured parity-violating asymmetries in elastic electron-proton scattering over the range of momentum transfers 0.12 < or =Q2 < or =1.0 GeV2. These asymmetries, arising from interference of the electromagnetic and neutral weak interactions, are sensitive to strange-quark contributions to the currents of the proton. The measurements were made at Jefferson Laboratory using a toroidal spectrometer to detect the recoiling protons from a liquid hydrogen target. The results indicate nonzero, Q2 dependent, strange-quark contributions and provide new information beyond that obtained in previous experiments.

Journal Article↗
PubMed2004

Precision measurement of the neutron spin asymmetryA(n)(1) and spin-flavor decomposition in the valence quark region.

We have measured the neutron spin asymmetry A(n)(1) with high precision at three kinematics in the deep inelastic region at x=0.33, 0.47, and 0.60, and Q(2)=2.7, 3.5, and 4.8 (GeV/c)(2), respectively. Our results unambiguously show, for the first time, that A(n)(1) crosses zero around x=0.47 and becomes significantly positive at x=0.60. Combined with the world proton data, polarized quark distributions were extracted. Our results, in general, agree with relativistic constituent quark models and with perturbative quantum chromodynamics (PQCD) analyses based on the earlier data. However they deviate from PQCD predictions based on hadron helicity conservation.

Journal Article↗
PubMed2004

[Selected emergencies in operative dermatology].

The large number of surgical procedures in many subspecialty areas of dermatology, such as dermatologic oncology, phlebology and aesthetic dermatology, raises the question of possible complications and emergency situations. Along with common complications such as post-operative bleeding, infections or flap necrosis, there are emergency situations which require immediate intervention to avoid significant harm to the patient. One must distinguish between dermatologic situations which require emergency surgery and emergencies that arise during or after dermatological surgery.

Anesthetics, Local↗
PubMed2004

Oral PUVA and topical steroids for treatment of oral manifestations of chronic graft-vs.-host disease.

BACKGROUND: Oral manifestations of chronic graft-vs.-host disease (cGVHD) can significantly affect the quality of life and severity often does not correlate with systemic manifestations. We evaluated the use of topical corticosteroids and the intraoral application of psoralen-UVA (PUVA) for treatment of oral manifestations of cGVHD. METHODS: Overall, 18 patients with oral manifestations of cGVHD were treated with either intraoral PUVA (n=7) or with topical corticosteroids (n=16). Four patients received intraoral PUVA after failure of topical steroids and one patient was treated with topical corticosteroids after failing treatment with intraoral PUVA. A glass fiber extension of an UVA source was used for manual intraoral application. Treatment with topical corticosteroids consisted of 0.1 mg/ml dexamethasone mouth wash four times a day in combination with antifungal prophylaxis. RESULTS: Four patients showed complete local response (CR) due to intraoral PUVA, two improved and one did not respond. Topical corticosteroids resulted in nine patients in CR, two improved and five did not respond. CONCLUSION: Intraoral PUVA as well as topical corticosteroids are effective in treatment of oral manifestations of oral GVHD with few side-effects and improve quality of life in patients with cGVHD.

Administration, Topical↗
PubMed2003

Amyloidosis of the seminal vesicle--a case report and review of the literature.

The finding of amyloid deposits in the seminal vesicles has been known for many years. The deposits are usually localized and asymptomatic. In recent years seminal vesicle amyloidosis has been reported to simulate prostate and bladder cancer invasion on MRI. We therefore feel that knowledge of the entity is important and present herein a typical case confirming the previous findings that amyloidosis of the seminal vesicles is a unique form of amyloidosis, a relatively common incidental finding and one that may be related to prostate cancer.

Amyloidosis↗
PubMed2003

Hidrosadenoma of the anal canal: a case report with review of the literature.

Hidrosadenoma of the anal canal is an extremely rare tumour. Only nine cases with similar histologic structure have been described in the literature, most representing tumours resected from the anal or rectal mucosa. We present a case of anal hidrosadenoma with immunohistochemical staining features identifying it as a true sweat gland tumour.

Adenoma, Sweat Gland↗
PubMed2002

In vivo pathogenicity of eight medically relevant Candida species in an animal model.

BACKGROUND: The relative pathogenicity of eight medically important Candida species was investigated in a mouse model. MATERIALS AND METHODS: Seventeen isolates were included; two isolates of Candida albicans, Candida glabrata, Candida tropicalis, Candida lusitaniae, Candida parapsilosis, Candida kefyr and Candida guilliermondii and three Candida krusei isolates. Mice in groups of three or four were inoculated with 10(5) and 10(7) CFU, respectively. On days 2 and 7 kidneys were removed, weighed and CFU/g kidney determined by the spot technique. RESULTS: Mortality was only observed in mice inoculated with C. albicans and C. tropicalis. Inoculated with 10(7) CFU C. tropicalis, C. glabrata, C. kefyr, C. lusitaniae, C. parapsilosis, C. krusei and C. guilliermondii the median log CFU/g kidney was significantly different: 6.0, 6.0, 6.4, 7.0, 3.7, < 2 and < 2 respectively (p < 0.0001). Eye infection and histological changes of kidneys were examined for C. albicans, C. tropicalis, C. glabrata and C. krusei-infected mice. Weight loss, kidney weight, inflammation and infection and number of eyes infected decreased with the pathogenicity of the four species. CONCLUSION: The virulence was highly different, illustrated by a 7-log difference in CFU/g kidney, a span of 0-100% mortality and histological changes in kidneys ranging from discrete to serious. The species could be divided into three groups with decreasing virulence: 1) C. albicans and C. tropicalis, 2) C. glabrata, C. kefyr and C. lusitaniae and 3) C. parapsilosis, C. krusei and C. guilliermondii. To our knowledge this is the first study with a simultaneous comparison of all eight species in an immunocompetent animal model.

Animals↗
PubMed2002

US-guided fine-needle aspiration biopsy of thyroid nodules.

PURPOSE: To determine which nodular areas provide most adequate and accurate material for cytology during US-guided fine-needle aspiration biopsy (FNAB) of thyroid nodules. MATERIAL AND METHODS: In a prospective multicentre study, US-guided FNAB (0.8 mm) was performed in 342 thyroid nodules (338 patients, 285 women, 18-83 years, 285 palpable). Histology was obtained in 169 nodules, revealing 75 neoplasms (44.4%) including 18 cancers (10.7%). In 206 solid nodules, 2 passes (central and peripheral) were compared. In 82 complex nodules, 2 passes (solid area and cystic area) were compared. RESULTS: The inadequacy rate was 16.4% and the false-negative rates were 2.2% and 28.1% for the diagnosis of cancer and neoplasm, respectively. In solid nodules, material was more adequate with peripheral passes compared to central passes, but the difference was not significant. In complex nodules, the inadequacy rate was much higher for passes in cystic areas (80.5%) compared to passes in solid areas (46.3%). CONCLUSION: Cystic areas due to degeneration seldom provided adequate material when aspirated. Aspiration should always be obtained from solid areas, at best using US-guidance. Adenomas and non-neoplastic nodules were difficult to distinguish.

Biopsy, Needle↗
PubMed2001

Protection of primary glial cells by grape seed proanthocyanidin extract against nitrosative/oxidative stress.

Previous studies showed that proanthocyanidins provide potent protection against oxidative stress. Here we investigate the effects of grape seed proanthocyanidin extract (GSPE) as a novel natural antioxidant on the generation and fate of nitric oxide (NO) in rat primary glial cell cultures. GSPE treatment (50 mg/L) increased NO production (measured by NO(2-) assay) by stimulation of the inducible isoform of NOS. However, GSPE failed to affect the LPS/IFN-gamma-induced NO production or iNOS expression. Similar responses were found in the murine macrophage cell line RAW264.7. GSPE did not show any effect on dihydrodichlorofluorescein fluorescence (ROS marker with high sensitivity toward peroxynitrite) either in control or in LPS/IFN-gamma-induced glial cultures even in the presence of a superoxide generator (PMA). GSPE treatment alone had no effect on the basal glutathione (GSH) status in glial cultures. Whereas the microglial GSH level declined sharply after LPS/IFN-gamma treatment, the endogenous GSH pool was protected when such cultures were treated additionally with GSPE, although NO levels did not change. Glial cultures pretreated with GSPE showed higher tolerance toward application of hydrogen peroxide (H(2)O(2)) and tert-butylhydroperoxide. Furthermore, GSPE-pretreated glial cultures showed improved viability after H(2)O(2)-induced oxidative stress demonstrated by reduction in lactate dehydrogenase release or propidium iodide staining. We showed that, in addition to its antioxidative property, GSPE enhances low-level production of intracellular NO in primary rat astroglial cultures. Furthermore, GSPE pretreatment protects the microglial GSH pool during high output NO production and results in an elevation of the H(2)O(2) tolerance in astroglial cells.

Animals↗
PubMed2001

High-dose stabilized chlorite matrix WF10 prolongs cardiac xenograft survival in the hamster-to-rat model without inducing ultrastructural or biochemical signs of cardiotoxicity.

WF10 is a stabilized chlorite matrix with immunosuppressive effects. In vitro studies have demonstrated its ability to suppress T cells and delay or abolish antigen presentation. Hence, WF10 may prove useful to prolong graft survival after transplantation. In this study, we evaluated the use of high dose WF10 as a single drug regimen in the hamster-to-rat xenotransplantation model and searched for possible cardiotoxic side effects. WF10 prolonged cardiac xenograft survival, but did not induce tolerence or inhibit pathological signs of acute rejection. Hamsters from the donor population, receiving high dose WF10 for 5 days, were compared with a matched control group. Ultrastructural examination of cardiac tissue as well as biochemical analysis of the cardiac enzymes troponin I, myoglobin and MB isoenzyme of creatine kinase showed no signs of damage. Thus, while prolonging graft survival, high dose WF10 seems to be non-cardiotoxic and as such should not contribute to the differential diagnosis of acute graft failure.

Animals↗