The LSF and MTF of rare-earth oxysulfide intensifying screens

The line spread function (LSF) and modulation transfer function (MTF) of 9 rare-earth screen/film systems were measured and compared with those of two fast calcium tungstate systems, using double-emulsion films sandwiched between two screens and mounted in regular cassettes. The LSFs were found to fit exponential functions. These results indicate that the increased sensitivity of rare-earth phosphors over calcium tungstate can be used to construct screens with a higher MTF or increased speed. The fast rare-earth systems allow the use of smaller focal spots for increased resolution while reducing the radiation dose to the patient.     

Immature teratoma of the ovary with a neural component ("solid" teratoma). A clinicopathologic study of 20 cases

Twenty cases of immature teratoma of the ovary with a neural component are analyzed. A plea is made for use of the nomenclature adopted from the new World Health Organization classification of ovarian tumors, the past confusion over terminology and histogenesis of this rare tumor is discussed. All the primary tumors in the present series contained at least some immature tissues (predominantly of neural origin) and were thus graded from 1 to 3 according to the criteria of Thurlbeck and Scully. No grade 0 tumors ("benign solid teratomas") were identified. We believe that thorough sectioning almost always insures the identification of immature elements. The prognosis was closely related to the histologic grade, but correlated poorly withthe clinical stage, the latter being influenced by the common finding (25 per cent of the cases in this series) of peritoneal implants composed exclusively of mature glial tissue, which is associated with a benign clinical evolution. This phenomenon of maturation or differentiation appears to be the rule rather than the exception in this tumor, since implants are usually of better or equal differentiation when compared with their primary tumors and older patients tend to have lower grade tumors than younger patients. Since the majority of patients with this tumor are young, primary surgical therapy should be conservative, unilateral salpingooophorectomy often being sufficient. Spontaneous or operative rupture of the tumor capsule carries an increased risk of subsequent dissemination. We have noted impressive clinical responses in patients with disseminated tumors of a high histologic grade after treatment with triple chemotherapy (vincristine, actinomycin D, and cyclophosphamide) but do not recommend adjuvant therapy in patients with only grade 0 implants.     

两种气体的热容分析

通过对多原子分子配分函数在常温情况下的具体讨论,详细分析了Ｏ２和ＣＯ２气体分子定压摩尔热容理论值与实验值差异的原因。     

The intrinsic structure and stability of out-of-alternation base pairs in Z-DNA

The inv(16) and related t(16;16) are found in 10% of all cases with de novo acute myeloid leukemia. In these rearrangements the core binding factor beta (CBFB) gene on 16q22 is fused to the smooth muscle myosin heavy chain gene (MYH11) on 16p13. To gain insight into the mechanisms causing the inv(16) we have analysed 24 genomic CBFB-MYH11 breakpoints. All breakpoints in CBFB are located in a 15-Kb intron. More than 50% of the sequenced 6.2 Kb of this intron consists of human repetitive elements. Twenty-one of the 24 breakpoints in MYH11 are located in a 370-bp intron. The remaining three breakpoints in MYH11 are located more upstream. The localization of three breakpoints adjacent to a V(D)J recombinase signal sequence in MYH11 suggests a V(D)J recombinase-mediated rearrangement in these cases. V(D)J recombinase-associated characteristics (small nucleotide deletions and insertions of random nucleotides) were detected in six other cases. CBFB and MYH11 duplications were detected in four of six cases tested.     

Aggressive angiomyxoma: findings on CT and MR imaging

OBJECTIVE: Aggressive angiomyxoma is a benign tumor affecting the pelvis and perineum, predominantly in women. Because of its variable presentation as a soft mass in the vulva, perianal region, buttock, or pelvis, the tumor is often clinically misdiagnosed and initial surgery is usually unsuccessful in extirpating it. This study describes the imaging features of these tumors. CONCLUSION: Aggressive angiomyxomas display unusual growth patterns of translevator extension with growth around perineal structures. Both CT and MR imaging show the transdiaphragmatic extent of these tumors. High signal intensity on T2-weighted MR images may reflect the myxomatous stroma of these tumors.     

Analysis of sheep T-cell receptor beta-chain heterogeneity

We analyzed nucleotide and deduced amino acid sequence heterogeneity of sheep T-cell receptor beta-chain cDNAs isolated from an anchored-polymerase chain reaction library. Evaluation of 34 individual rearrangements has defined 18 new beta-chain variable region sequences which have been clustered into 13 families. Presumptive allelic polymorphisms of four of these variable regions have been defined, as well as ten distinct beta-chain joining region sequences. The present analysis indicates that sheep T-cell receptor beta-chains are composed of characteristic leader, variable, joining, and constant region sequences, and that imprecise joining and N-region addition contribute significantly to diversity in the third hypervariable region. Thus, it appears that sheep, like all other mammals studied to date, employ somatic rearrangement of multiple germline genes to create beta-chain heterogeneity. These findings have allowed us to estimate the diversity of the sheep T-cell receptor beta-chain variable region repertoire, and they provide information that will permit the evaluation of the role that specific T-cell populations play in naturally occurring and experimental diseases of sheep.