The computed tomographic (CT) scans of 30 patients with solitary bronchioloalveolar carcinoma were reviewed. Common features at CT included the peripheral or subpleural location of a pulmonary mass (25 cases), pseudocavitation (18 cases), heterogeneous attenuation (17 cases), irregular margins forming a star pattern (22 cases), and pleural tags (21 cases). Using these CT criteria, four independent observers attempted to identify cases of bronchioloalveolar carcinoma from a larger sample of lung cancers and benign lesions by categorizing a series of test cases into four probability categories. Although the bronchioloalveolar carcinomas were correctly ranked in the two highest probability categories 75% of the time (in 45 of 60 cases), there was considerable overlap with other lung lesions, particularly with adenocarcinoma and large cell undifferentiated carcinoma. However, even though the typical features of bronchioloalveolar carcinoma are not invariable or highly specific, they are characteristic enough to suggest the diagnosis. 相似文献
A 13C NMR analysis of the methyl and ethyl end-groups in isotactic polypropylene, prepared in the presence of TiCl3- and Til3-based catalysts, was performed and the isotactic regularity of the first propylene unit added to the Ti—alkyl bond was measured. In the presence of the catalyst Til3/Al(13CH2CH3)3 the stereoregulating effects derived from the ethyl and iodine ligands are cooperative, so that the addition of the first monomeric unit is as isotactic as the following propagation steps. A comparison of the chain end-groups of polypropylene obtained in the presence of different catalysts shows that the extent of steric control upon insertion of the first monomer molecule results not only from the presence of alkyl titanium ligands larger than methyl and of titanium halide ligands larger than chlorine, but also from mutual ligand interactions. 相似文献
The gene for the most frequent from of X-linked retinitis pigmentosa
(XLRP), RP3, has been assigned by genetic and physical mapping to a segment
of less than 1000 kbp, which is flanked by the marker DXS1110 and the
ornithine transcarbamylase (OTC) gene. In search of microdeletions, we have
screened the DNA of 30 unrelated patients with XLRP by employing a
representative set of YAC-derived DNA fragments that were generated by
restriction enzyme digestion and PCR amplification. In one of these
patients, a 6.4 kbp microdeletion was detected which was not present in the
DNA of 444 male controls. A cosmid contig spanning the deletion was
constructed and used to isolate cDNAs from retina-specific libraries. Exons
corresponding to these expressed sequences as well as other putative exons
were identified by sequencing more than 30 kbp of the critical region. So
far, no point mutations in these putative exon sequences have been
identified.
相似文献
The gene for retinitis pigmentosa 3 (RP3), the most frequent form of X-
linked RP (XLRP), has been mapped previously to a chromosome interval of
less than 1000 kbp between the DXS1110 marker and the OTC locus at
Xp21.1-p11.4. Employing a novel technique, YAC Representation Hybridization
(YRH)', we have recently identified a small XLRP associated microdeletion
in this interval, as well as several putative exons including the 3' end of
a gene that was truncated by the deletion. cDNA library screening and
sequencing of a cosmid centromeric to the deletion has now enabled us to
identify numerous additional exons and to detect several point mutations in
patients with XLRP. The predicted gene product shows homology to RCC1, the
guanine-nucleotide- exchange factor (GEF) of the Ras-like GTPase Ran. Our
findings suggest that we have cloned the long-sought RP3 gene, and that it
may encode the GEF of a retina-specific GTP-binding protein.
相似文献
Copolymers of ethylene (E) with norbornene (N) were synthesized using the catalysts rac‐Et(Ind)2ZrCl2/MAO ( 1 ), 90%rac/10%meso‐Et(4,7‐Me2Ind)2ZrCl2/MAO ( 2 ), and rac‐H2C(3‐t‐BuInd)2ZrCl2/MAO ( 3 ). Catalyst activity, molar mass (MM), and copolymer composition were studied as a function of time. The polymers showed an unusually narrow molar mass distribution (MMD) and a significant increase of their MM with time for up to one hour, suggesting a “quasi‐living” polymerization at 30 °C. The experimental data were fitted to kinetic equations and the propagation and transfer reactions were described in quantitative terms. Norbornene greatly depressed the propagation rate, along with the chain transfer rate. The more sterically hindered catalysts of the series showed lower propagation and chain transfer turnover frequency than 1 and yielded polymers with a low ( 2 ) to very low ( 3 ) norbornene content. The presence of norbornene in solution seemed to be one of the main factors responsible for the observed “quasi‐living” character of the copolymerization, probably due to coordination of norbornene to the active site. Time‐resolved kinetic studies also allowed for the calculation of the fraction of active metal centers, ranging from 56% ( 3 ) and 66–68% ( 1 ) to 94% ( 2 ) of the total zirconium present, depending on catalyst structure.
Left: molar mass (top) and polydispersity (bottom) as a function of the normalized polymer yield. The dashed line is the theoretical curve for ideal living polymerization. Catalysts 1 (□), 2 (?), and 3 (○) at N/E ratio 12.5 and catalyst 1 (?) at N/E ratio 28.4. Right: enlargement of the low yield section. 相似文献
Ethylene polymerizations and norbornene oligomerizations catalysed by Cp2Ti13CH3Cl/MAO (Cp: cyclopentadienyl; MAO: methylaluminoxane) mixtures have been carried out at different temperatures (from -20°C to 20°C), in order to test the validity of carbene mechanisms in α-olefin polymerizations. Depending on the temperature, different ratios of the cationic species [Cp2Ti13CH3]+[Cl · MAO]? and precursors of the alkylidene Cp2Ti = 13CH2 exist. The in situ polymerization of 13C enriched ethylene was monitored by 13C NMR spectroscopy. Moreover, catalytic activity was determined and polyethylene samples were analyzed by 13C NMR and gel permeation chromatography (GPC). The following evidence has been provided against the carbene mechanism in the α-olefin polymerization with titanocene based catalysts: (a) in the in situ ethylene polymerization experiments the appearance of polyethylene signals is concurrent with the decrease of cationic [Cp2Ti13CH3]+[Cl · MAO]? signals and is not related to the intensity of the alkylidene Cp2Ti = 13CH2 signals; (b) from the 13C NMR analysis of polyethylene chain-end groups the 13C enrichment of Cp2Ti13CH3Cl has only been found in the methyl chain-end group and not in the methylene of the propyl chain-end group, as should have been the case if the carbene mechanism had been valid; (c) from norbornene oligomerization (at 0°C) the addition product 2-13C enriched methyl-norbornane has been identified. Moreover, the identification of a 13C enriched methylidene-norbornane dimer at higher temperatures has revealed the possibility of norbornene addition to titanium carbenes through the formation of titanacyclobutane without the opening of the norbornene ring. However, this process requires higher energies with respect to the Cossee type insertion. 相似文献
A comprehensive mutational scanning test for the p53 coding region based on
multiplex PCR and two-dimensional DNA electrophoresis was designed and
evaluated. In a 2-step multiplex PCR, the p53 coding region (exons 2-11)
was amplified as a single 8646-bp fragment by long- distance PCR in step
one. This fragment served as a template for the subsequent co-amplification
of the individual exons in two multiplex groups in step two. The multiplex
products were then separated, first on the basis of size in non-denaturant
polyacrylamide gels and then on the basis of sequence by denaturing
gradient gel electrophoresis (DGGE). Primers for optimal PCR, melting
behavior and 2-D gel distribution were designed using a recently developed
computer program. The resulting two-dimensional gene scanning (TDGS) test
was evaluated by screening, in a blinded fashion, 29 coded DNA samples from
Li- Fraumeni syndrome patients with previously identified germline
mutations. All mutations were correctly detected. This assay provides an
accurate, cost-effective and non-radioactive method for simultaneous
mutational scanning of all p53 coding exons.
相似文献
This molecular epidemiologic case-control study of lung cancer incorporated
three complementary biomarkers: the glutathione S- transferase M1 (GSTM1)
null genotype, a potential marker of susceptibility, and polycyclic
aromatic hydrocarbon-DNA adducts (PAH- DNA) and sister chromatid exchanges
(SCE), both indicators of environmentally induced genetic damage.
Associations between biomarkers and lung cancer were investigated, as were
possible gene-environment interactions between the GSTM1 null genotype and
tobacco smoke exposure. Subjects included 136 primary non-small cell lung
cancer surgical patients and 115 controls at the Columbia Presbyterian
Medical Center. Questionnaire and Tumor Registry data, pre-treatment blood
samples and biomarker measurements on blood were obtained. Overall, GSTM1
null genotype was significantly associated with lung cancer [odds ratio
(OR) = 2.04, 95% confidence interval (CI) = 1.13-3.68]. ORs for GSTM1 and
lung cancer were significant in females (2.50, 1.09-5.72) and smokers
(2.25, 1.11-4.54) and not significant in males (1.4, 0.58-3.38) and
non-smokers (0.88, 0.18-4.33). However, ORs for males versus females and
smokers versus non-smokers did not differ significantly. The OR for GSTM1
and lung cancer in female smokers was 3.03 (1.09- 8.40), compared with 1.42
(0.53-4.06) in male smokers. In contrast to PAH-DNA adducts in leukocytes,
SCE did not differ between cases and controls. Neither biomarker differed
significantly between the two GSTM1 genotypes. The combined effect of
elevated PAH-DNA adducts and GSTM1 genotype on case-control status (16.19,
1.2-115) appeared multiplicative. Results suggest that the effect of the
GSTM1 null genotype is greatest in female smokers, which is consistent with
other evidence that indicates that women are at higher risk of lung cancer
than males, given equal smoking. Persons with both the GSTM1 deletion and
elevated PAH-DNA adducts may represent a sensitive subpopulation with
respect to carcinogens in tobacco smoke and other environmental media.
相似文献
It has been suggested that activation of tissue phospholipases may contribute to the development of ischemic cell injury. In the present study we sought to assess whether administration of the phospholipase inhibitor quinacrine would reduce the extent of myocardial necrosis after coronary artery occlusion. In open-chest, anesthetized dogs the left anterior descending coronary artery was ligated, and technetium-99-labeled albumin microspheres were injected into the left atrium to measure the area at risk. The animals were then randomly divided into a control group (n = 8) and a group receiving quinacrine (5 mg/kg intravenous bolus followed by a 40 micrograms/kg/min infusion for 6 hours; n = 9). The animals were killed 6 hours after occlusion, and the infarcted area was delineated by triphenyltetrazolium chloride staining. The extent of the risk region was similar in the two groups (32.3 +/- 2.1% of the left ventricle in control dogs and 34.2 +/- 3.4% in quinacrine-treated dogs). Infarct size was 86.4 +/- 8.8% of the risk region in control animals, whereas in treated dogs it averaged 62.3 +/- 6.4% of the risk region (p = 0.05). No differences were found in heart rate, arterial pressure, and rate-pressure product between the two groups. Thus administration of the phospholipase inhibitor quinacrine reduced the extent of myocardial necrosis in a model of fixed coronary artery occlusion. Preservation of membrane phospholipids, reduced formation of lipoxygenase metabolites, or both may mediate this phenomenon. 相似文献