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991.
We demonstrate that c-myc gene expression is essential for growth of breast cancer cells. It also plays an important role in the progression of human breast cancer. c-myc gene amplification may be important for cancer cell invasion, but perhaps not essential for nodal metastasis. We also provide compelling evidence that the c-myc oncogene is an estrogen target gene in hormone-responsive breast cancer. Hormonal progression of breast cancer could be brought about by the enhanced expression of the c-myc gene, with gene amplification and enhanced c-myc mRNA stability being two major mechanisms involved.  相似文献   
992.
PURPOSE: An international consensus on the criteria for surgicopathologic staging (INSS) of patients with neuroblastoma has been published, but has not been validated. A retrospective study was conducted to assess if the INSS definitions identified prognostic subsets of patients with neuroblastoma. PATIENTS AND METHODS: The initial operative and pathology reports were reviewed from 675 patients on Pediatric Oncology Group (POG) #8104, a stage- and age-related treatment study that used the POG surgicopathologic staging system. RESULTS: Of 596 eligible cases, there was concordance between the POG and INSS stages for the 193 patients with localized, resected disease (POG stage A), the 202 with distant metastases, the 51 with POG stage Ds (IVs) tumors, and 40 of the cases with grossly unresected, localized tumor without lymph node involvement (POG stage B). Of the remaining 19 patients with POG stage B tumors, five were INSS stage 2B and 14 INSS stage 3. All of the 91 cases with nonadherent, regional lymph node metastases (POG stage C) conformed to the definitions for INSS stage 2B (n = 42) or 3 (n = 49). In infants, there was no difference in event-free survival (EFS) among INSS stages 2A, 2B, or 3. In contrast, older children with INSS stage 3 disease had inferior EFS compared with INSS stage 2A or 2B tumors. CONCLUSION: We conclude the following: (1) the INSS identifies distinct patient subsets, particularly in children; (2) infants remain a favorable group, regardless of INSS/POG stage; and (3) the INSS deserves further prospective study especially in the light of recent biologic prognostic variables.  相似文献   
993.
Proliferative enteritis (PE) is a common intestinal disease on pig farms. The disease is caused by ileal symbiont (IS) intracellularis (Campylobacter-like organisms) bacteria. An enzyme-linked immunosorbent assay (ELISA) was developed to measure IS intracellularis-specific immunoglobulin G (IgG) response in the sera of pigs. The antigen used in the ELISA was filtered, percoll gradient-purified IS intracellularis extracted from the intestines of pigs affected with proliferative hemorrhagic enteropathy. The antibody responses of pigs challenged with intestinal homogenates from pigs affected with proliferative hemorrhagic enteropathy containing IS intracellularis or percoll-gradient purified IS intracellularis were low and variable. The low IgG titers measured in challenged pigs support previous findings that IgG plays a minor role in the immune response of pigs to IS intracellularis. On a farm in which infection was endemic, pigs seroconverted at between 7 and 24 weeks of age. High IgG titers, indicative of maternally acquired antibody, were present in 3-week-old pigs. The IgG titers in piglets were lowest at 6 weeks of age, which approximates the age of onset of clinical disease. These results suggest that IgG plays a role in determining the susceptibilities of pigs to natural infection. Measurements of seroconversion by the ELISA might aid in epidemiological investigations of PE in naturally infected herds. However, the variable antibody responses in experimentally challenged pigs would seem to limit its usefulness as an antemortem diagnostic test for PE.  相似文献   
994.
995.
During the period from September 1988 to April 1990, mosquitoes were captured using Shannon light trap and Falc?o light traps, in Terra Boa county, in the north of Paraná State, Brazil. The Shannon trap was installed in the outlying modified forest and Falc?o traps were installed in the modified forest and domiciliary areas. The prevalence of species was verified and the methods of capture compared.  相似文献   
996.
997.
998.
The N-terminal cluster binding motif Cys8XXXXXXXCys16....Cys49 of Bacillus schlegelii 7Fe ferredoxin, which provides the ligands to the [Fe3S4]+ cluster, was modified by the mutation Asp13 --> Cys. The mutant D13C is expressed in Escherichia coli as an 8Fe ferredoxin, with NMR properties similar to those of clostridial-type ferredoxins. The full assignment of the hyperfine shifted resonances indicates that Cys13 serves as ligand to the new fourth iron atom in the N-terminal cluster despite the atypical binding sequence CysXXXXCysXXCys....Cys. The C alpha-C beta-S-Fe dihedral angles of all cysteine ligands to the two [Fe4S4]2+ clusters of the D13C variant are similar to those observed in other 8Fe and 4Fe ferredoxins.  相似文献   
999.
The primary structures of two subunits of an alpha-amylase inhibitor (alpha AI-2) from a wild common bean (Phaseolus vulgaris) were revealed by a comparison of the amino acid sequence previously deduced from the nucleotide sequence with the amino- and carboxyl-terminal amino acid sequences determined by conventional methods. The polypeptide molecular weight of alpha AI-2 obtained by the light-scattering technique, considered together with the sequence molecular weights revealed for the subunits, indicated that alpha AI-2 has the subunit stoichiometry of an alpha 2 beta 2 complex. These structural features were closely similar to those recently elucidated for a white kidney bean (P. vulgaris) alpha-amylase inhibitor, which is quite different in the inhibitory specificity from alpha AI-2. The post-translational processing of the precursor glycoproteins to form the tetrameric structure appeared to require an Arg residue close to the processing site. Further, the proper associations of the subunits into the tetrameric structures seemed to be strictly controlled by a few amino acids on the subunit interfaces.  相似文献   
1000.
This case describes a unique complication of silicone breast implantation that is previously undocumented. Internal mammary silicone lymphadenopathy mimicking breast cancer recurrence represents an important new clinical entity. The diagnosis and management of this clinical enigma are challenging. In our patient, videothoracoscopy proved to be minimally invasive and allowed complete resection of the entire chain of pathologic nodes. Explantation of the silicone prostheses and complete capsulectomy are indicated. Light microscopy alone can suggest the diagnosis of silicone lymphadenopathy. Infrared spectral analysis can be a helpful adjunct to allow an unequivocal diagnosis.  相似文献   
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