390 research outputs found
Impact of geometric properties of silica supports on metallocene catalyst behavior
The objective of this work was to evaluate the effect of the physical properties of several different commercial silicas on the performance of metallocene catalysts when used in gas and slurry phase polymerization. A lot is known about how the chemistry of the silica effects the polymerization and the final product, but very little is described in the literature concerning parameters such as pore volume and pore diameter. This work dealt with these issues by using two different metallocenes in homo and copolymerization of ethylene and ethylene 1-hexene respectively.
In terms of silica porosity, the metallocene/MAO catalyst supported on the silica with lower pore volume appears to polymerize faster than the one which is supported on the silica with higher pore volume. This behavior can be attributed to [email protected]
the fact that the fragmentation of the growing catalyst/polymer particle with lower pore volume will be faster than its counterpart.
In terms of mean particle size, if other physical properties like pore volume, pore diameter and surface area of the silica supported metallocene/MAO catalysts are kept similar along with the metal loadings, the smaller catalyst particles are more active than their bigger counterparts. This effect of particle size on instantaneous activity seems to be the same at different monomer pressures and in the presence and absence of a comonomer (like 1-hexene).
Finally, the effect of pore diameter is very complex. The normal trend would be the smaller the pore diameter the faster the polymerization should be, due to the reasons explained for the pore volume. However, by using the technique we employed for the previous parameters, it was not possible to draw a valid conclusion. It seems that MAO penetration depends on the pore size, and that it might not penetrate into particles with small pore diameters
Suspected congenital hyperinsulinism in a Shiba Inu dog
A 3-month-old male intact Shiba Inu dog was evaluated for a seizure disorder initially deemed idiopathic in origin. Seizure frequency remained unchanged despite thera- peutic serum phenobarbital concentration and use of levetiracetam. The dog was documented to be markedly hypoglycemic during a seizure episode on reevaluation at 6 months of age. Serum insulin concentrations during hypoglycemia were 41 U/μL (reference range, 10-29 U/μL). The dog was transitioned to 4 times per day feeding, diazoxide was started at 3.5 mg/kg PO q8h, and antiepileptic drugs were discon- tinued. No clinically relevant abnormalities were identified on bicavitary arterial and venous phase contrast computed tomographic imaging. The dog remained seizure- free and clinically normal at 3years of age while receiving 5.5 mg/kg diazoxide PO q12h and twice daily feeding. Seizures later occurred approximately twice per year and after exertion, with or without vomiting of a diazoxide dose. Blood glucose curves and interstitial glucose monitoring were used to titrate diazoxide dose and dosing interval. Congenital hyperinsulinism is well recognized in people but has not been reported in veterinary medicine
A “rose is a rose is a rose is a rose,” but exactly what is a gastric adenocarcinoma?
No abstract.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/34520/1/1_ftp.pd
Gene expression changes with differentiation of cord blood stem cells to respiratory epithelial cells: a preliminary observation
Resveratrol has antiinflammatory and antifibrotic effects in the peptidoglycan‐polysaccharide rat model of Crohn's disease
Background: Resveratrol has antiinflammatory and antifibrotic effects. Resveratrol decreases proliferation and collagen synthesis by intestinal smooth muscle cells. We hypothesized that resveratrol would decrease inflammation and fibrosis in an animal model of Crohn's disease. Methods: Peptidoglycan‐polysaccharide (PG‐PS) or human serum albumin (HSA) was injected into the bowel wall of Lewis rats at laparotomy. Resveratrol or vehicle was administered daily by gavage 1–27 days postinjection. On day 28, gross abdominal and histologic findings were scored. Cecal collagen content was measured by colorimetric analysis of digital images of trichrome‐stained sections. Cecal levels of procollagen, cytokine, and growth factor mRNAs were determined. Results: PG‐PS‐injected rats (vehicle‐treated) developed more fibrosis than HSA‐injected rats by all measurements: gross abdominal score ( P < 0.001), cecal collagen content ( P = 0.04), and procollagen I and III mRNAs ( P ≤ 0.0007). PG‐PS‐injected rats treated with 40 mg/kg resveratrol showed a trend toward decreased gross abdominal score, inflammatory cytokine mRNAs, and procollagen mRNAs. PG‐PS‐injected rats treated with 100 mg/kg resveratrol had lower inflammatory cytokine mRNAs (IL‐1β [3.50 ± 1.08 vs. 10.79 ± 1.88, P = 0.005], IL‐6 [17.11 ± 9.22 vs. 45.64 ± 8.83, P = 0.03], tumor necrosis factor alpha (TNF‐α) [0.80 ± 0.14 vs. 1.89 ± 0.22, P = 0.002]), transforming growth factor beta 1 (TGF‐β1) mRNA (2.24 ± 0.37 vs. 4.06 ± 0.58, P = 0.01), and histologic fibrosis score (6.4 ± 1.1 vs. 9.8 ± 1.0; P = 0.035) than those treated with vehicle. There were trends toward decreased gross abdominal score and decreased cecal collagen content. Procollagen I, procollagen III, and IGF‐I mRNAs also trended downward. Conclusions: Resveratrol decreases inflammatory cytokines and TGF‐β1 in the PG‐PS model of Crohn's disease and demonstrates a promising trend in decreasing tissue fibrosis. These findings may have therapeutic applications in inflammatory bowel disease. (Inflamm Bowel Dis 2011;)Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90530/1/21843_ftp.pd
Polska wersja kwestionariusza oceny jakości życia u dorosłych pacjentów z niedoborem hormonu wzrostu - 4-etapowy proces tłumaczenia i walidacji
Introduction: The Quality of Life Assessment of Growth Hormone Deficiency in Adults (QoL-AGHDA) was developed simultaneously in
five languages (English, Swedish, German, Italian and Spanish) to measure quality of life (QoL) in adult patients with Growth Hormone
(GH) deficiency. The aim of the project was to produce a validated Polish version of the QoL-AGHDA that was conceptually equivalent to
the UK-English version.
Material and methods: Translation and validation procedure consisted of 4 stages. Stage 1: A bilingual translation panel [7 participants,
fluent in both English and Polish (Polish as their first language) with university education] translated the questionnaire. Stage 2: A lay
translation panel (6 participants of an average to lower than average educational level, speaking only the target language) reviewed the
wording of the draft version produced by bilingual panel to improve clarity and immediacy. Stage 3: The translated questionnaire was
then field-tested with 15 adults with GH deficiency. Stage 4: Finally, the amended version underwent psychometric evaluation to check its
reliability and validity (it was administered to 85 GH-deficient adults on two occasions, two weeks apart).
Results: The Polish QoL-AGHDA version was successfully adapted and it is characterized by a high degree of reliability and validity. The
test-retest reliability coefficient for the Polish QoL-AGHDA was 0.92. The Cronbach’s Alpha coefficient for the Polish QoL-AGHDA was
0.91 (N = 70) at Time 1 and 0.94 (N = 79) at Time 2. Correlation between QoL-AGHDA and Nottingham Health Profile items confirmed
high convergent and divergent validity.
Conclusions: The Polish QoL-AGHDA is a reliable and valid measure of QoL suitable for use in clinical studies and routine clinical
practice. (Pol J Endocrinol 2008; 59 (5): 374-384)Wstęp: Kwestionariusz QoL-AGHDA (Quality of Life Assessment of Growth Hormone Deficiency in Adults) został opracowany w 5 językach
(angielskim, szwedzkim, niemieckim, włoskim i hiszpańskim) w celu oceny jakości życia (QoL, quality of life) u pacjentów dorosłych
z niedoborem hormonu wzrostu (GH, growth hormone). Celem obecnej pracy było opracowanie walidowanej polskiej wersji QoL-AGHDA,
równoważnej koncepcyjnie z wersją angielską.
Materiał i metody: Proces tłumaczenia i walidacji składał się z 4 etapów. Etap 1: Tłumaczenie kwestionariusza z języka angielskiego na
język polski [uczestniczyło w nim 7 osób z wyższym wykształceniem, płynnie posługujących się językiem angielskim i polskim (przy
czym język polski był ich językiem ojczystym)]. Etap 2: Etap "roboczy" - zweryfikowanie słownictwa zastosowanego na etapie 1 w celu
poprawienia przejrzystości i stopnia zrozumienia przetłumaczonego kwestionariusza (uczestniczyło w nim 6 osób z podstawowym lub średnim wykształceniem, posługujących się wyłącznie językiem polskim). Etap 3: Ocena przetłumaczonego kwestionariusza przez pacjentów
grupy docelowej w celu jego ewentualnego zweryfikowania (uczestniczyło w nim 15 dorosłych pacjentów z niedoborem GH).
Etap 4: Psychometryczna ocena zweryfikowanej polskiej wersji kwestionariusza, mająca na celu sprawdzenie jego wiarygodności (niezawodności)
i trafności tłumaczenia (uczestniczyło w nim 85 dorosłych pacjentów z niedoborem GH, których dwukrotnie, w odstępie
dwutygodniowym, poproszono o wypełnienie kwestionariusza).
Wyniki: Polska wersja QoL-AGHDA została pomyślnie zaadaptowana i charakteryzuje się ona wysoką wiarygodnością (niezawodnością)
i trafnością tłumaczenia. Współczynnik wiarygodności (niezawodności) obliczony za pomocą metody powtórnego testowania wyniósł 0,92.
Współczynnik Cronbacha, w pierwszym i drugim badaniu na etapie 4 walidacji, wyniósł odpowiednio 0,91 (N = 70) i 0,94 (N = 79). Korelacja
pomiędzy wartościami uzyskanymi w kwestionariuszach QoL-AGHDA i NHP (Nottingham Health Profile) potwierdziła wysoki stopień
zbieżnej i rozbieżnej trafności polskiej wersji QoL-AGHDA.
Wnioski: Polska wersja QoL-AGHDA pozwala na wiarygodną (niezawodną) i trafną ocenę jakości życia i może być stosowana zarówno
w badaniach klinicznych, jak i w codziennej praktyce lekarskiej. (Endokrynol Pol 2008; 59 (5): 374-384
Evidence for an FU Orionis-like Outburst from a Classical T Tauri Star
We present pre- and post-outburst observations of the new FU Orionis-like
young stellar object PTF 10qpf (also known as LkHa 188-G4 and HBC 722). Prior
to this outburst, LkHa 188-G4 was classified as a classical T Tauri star on the
basis of its optical emission-line spectrum superposed on a K8-type
photosphere, and its photometric variability. The mid-infrared spectral index
of LkHa 188-G4 indicates a Class II-type object. LkHa 188-G4 exhibited a steady
rise by ~1 mag over ~11 months starting in Aug. 2009, before a subsequent more
abrupt rise of > 3 mag on a time scale of ~2 months. Observations taken during
the eruption exhibit the defining characteristics of FU Orionis variables: (i)
an increase in brightness by > 4 mag, (ii) a bright optical/near-infrared
reflection nebula appeared, (iii) optical spectra are consistent with a G
supergiant and dominated by absorption lines, the only exception being Halpha
which is characterized by a P Cygni profile, (iv) near-infrared spectra
resemble those of late K--M giants/supergiants with enhanced absorption seen in
the molecular bands of CO and H_2O, and (v) outflow signatures in H and He are
seen in the form of blueshifted absorption profiles. LkHa 188-G4 is the first
member of the FU Orionis-like class with a well-sampled optical to mid-infrared
spectral energy distribution in the pre-outburst phase. The association of the
PTF 10qpf outburst with the previously identified classical T Tauri star LkHa
188-G4 (HBC 722) provides strong evidence that FU Orionis-like eruptions
represent periods of enhanced disk accretion and outflow, likely triggered by
instabilities in the disk. The early identification of PTF 10qpf as an FU
Orionis-like variable will enable detailed photometric and spectroscopic
observations during its post-outburst evolution for comparison with other known
outbursting objects.Comment: 14 pages, 11 figures, ApJ accepte
Arrhythmogenic Right Ventricular Cardiomyopathy: Characterization of Left Ventricular Phenotype and Differential Diagnosis With Dilated Cardiomyopathy
Background This study assessed the prevalence of left ventricular (LV) involvement and characterized the clinical, electrocardiographic, and imaging features of LV phenotype in patients with arrhythmogenic right ventricular cardiomyopathy (ARVC). Differential diagnosis between ARVC-LV phenotype and dilated cardiomyopathy (DCM) was evaluated. Methods and Results The study population included 87 ARVC patients (median age 34\ua0years) and 153 DCM patients (median age 51\ua0years). All underwent cardiac magnetic resonance with quantitative tissue characterization. Fifty-eight ARVC patients (67%) had LV involvement, with both LV systolic dysfunction and LV late gadolinium enhancement (LGE) in 41/58 (71%) and LV-LGE in isolation in 17 (29%). Compared with DCM, the ARVC-LV phenotype was statistically significantly more often characterized by low QRS voltages in limb leads, T-wave inversion in the inferolateral leads and major ventricular arrhythmias. LV-LGE was found in all ARVC patients with LV systolic dysfunction and in 69/153 (45%) of DCM patients. Patients with ARVC and LV systolic dysfunction had a greater amount of LV-LGE (25% versus 13% of LV mass; P<0.01), mostly localized in the subepicardial LV wall layers. An LV-LGE 6520% had a 100% specificity for diagnosis of ARVC-LV phenotype. An inverse correlation between LV ejection fraction and LV-LGE extent was found in the ARVC-LV phenotype (r=-0.63; P<0.01), but not in DCM (r=-0.01; P=0.94). Conclusions LV involvement in ARVC is common and characterized by clinical and cardiac magnetic resonance features which differ from those seen in DCM. The most distinctive feature of ARVC-LV phenotype is the large amount of LV-LGE/fibrosis, which impacts directly and negatively on the LV systolic function
Combining fMRI and DISC1 gene haplotypes to understand working memory-related brain activity in schizophrenia
Altres ajuts: Ministerio de Ciencia e Innovación; Fondo Europeo de Desarrollo Regional (FEDER); European Social Fund ("Investing in your future"); Generalitat de Catalunya, Departament de Salut (SLT017/20/000233).The DISC1 gene is one of the most relevant susceptibility genes for psychosis. However, the complex genetic landscape of this locus, which includes protective and risk variants in interaction, may have hindered consistent conclusions on how DISC1 contributes to schizophrenia (SZ) liability. Analysis from haplotype approaches and brain-based phenotypes can contribute to understanding DISC1 role in the neurobiology of this disorder. We assessed the brain correlates of DISC1 haplotypes associated with SZ through a functional neuroimaging genetics approach. First, we tested the association of two DISC1 haplotypes, the HEP1 (rs6675281-1000731-rs999710) and the HEP3 (rs151229-rs3738401), with the risk for SZ in a sample of 138 healthy subjects (HS) and 238 patients. This approach allowed the identification of three haplotypes associated with SZ (HEP1-CTG, HEP3-GA and HEP3-AA). Second, we explored whether these haplotypes exerted differential effects on n-back associated brain activity in a subsample of 70 HS compared to 70 patients (diagnosis × haplotype interaction effect). These analyses evidenced that HEP3-GA and HEP3-AA modulated working memory functional response conditional to the health/disease status in the cuneus, precuneus, middle cingulate cortex and the ventrolateral and dorsolateral prefrontal cortices. Our results are the first to show a diagnosis-based effect of DISC1 haplotypes on working memory-related brain activity, emphasising its role in SZ
Treatment of arrhythmogenic right ventricular cardiomyopathy/dysplasia: an international task force consensus statement
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