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Biomedical subjects

M S Yao

Publications and source records attributed to M S Yao.

7 recordsLinked to original sources
PubMed2006

Posterior epidural migration of a sequestrated lumbar disk fragment: MR imaging findings.

We present a 75-year-old man who, for 2 weeks, had progressive pain in both of his thighs when standing straight. MR imaging showed a sequestrated disk fragment, which had a signal intensity similar to that of a herniated disk with a rim enhancement in the posterior epidural space and a ruptured outermost annulus of the intervertebral disk at L2-3. Awareness of these MR imaging findings can help in the diagnosis of posterior epidural disk migration.

Aged↗
PubMed2001

Endobronchial brachytherapy.

High-dose rate endobronchial brachytherapy is a well-tolerated out-patient procedure that provides a high likelihood for durable palliation of symptoms associated with endobronchial tumor. The most significant associated toxicity is late massive hemoptysis, the risk for which can be minimized by careful treatment planning and limiting the size of the delivered dose per fraction to less than 10 Gy, prescribed at 1 cm distance.

Brachytherapy↗
PubMed1999

Disruption of mRad50 causes embryonic stem cell lethality, abnormal embryonic development, and sensitivity to ionizing radiation.

The Mre11/Rad50 protein complex functions in diverse aspects of the cellular response to double-strand breaks (DSBs), including the detection of DNA damage, the activation of cell cycle checkpoints, and DSB repair. Whereas genetic analyses in Saccharomyces cerevisiae have provided insight regarding DSB repair functions of this highly conserved complex, the implication of the human complex in Nijmegen breakage syndrome reveals its role in cell cycle checkpoint functions. We established mRad50 mutant mice to examine the role of the mammalian Mre11/Rad50 protein complex in the DNA damage response. Early embryonic cells deficient in mRad50 are hypersensitive to ionizing radiation, consistent with a role for this complex in the repair of ionizing radiation-induced DSBs. However, the null mrad50 mutation is lethal in cultured embryonic stem cells and in early developing embryos, indicating that the mammalian Mre11/Rad50 protein complex mediates functions in normally growing cells that are essential for viability.

Animals↗
PubMed1997

The effect of M-stage on patterns of failure in posterior fossa primitive neuroectodermal tumors treated on CCG-921: a phase III study in a high-risk patient population.

PURPOSE: To analyze patterns of failure in patients (pts) with high-risk posterior fossa primitive neuroectodermal tumors (PF-PNETs) treated with combined modality therapy on a large, randomized multiinstitutional study. METHODS AND MATERIALS: One hundred eighty-eight prospectively staged pts with PF-PNET confirmed by central pathology review, with high-risk features, were treated on Children's Cancer Group Study 921 (CCG-921), comparing two chemoradiotherapy regimens. Patterns of initial sites of failure were analyzed, specifically evaluating the impact of Chang M-stage. RESULTS: Progression-free survival (PFS) correlated with the presence or absence of metastatic disease (p < 0.001), with 5-year PFS of 68 +/- 5.8% for M0 vs. 43 +/- 6.8% for M+ pts. The cumulative incidence functions (CIF) of recurrence were different (p = 0.005) and at 5 years were 29 +/- 4.7% for M0 pts and 48 +/- 5.5% for M+ pts. Involvement of the PF at time of initial failure as measured by CIF correlated with M-stage (p = 0.047) and occurred in 18 +/- 3.9% of M0 pts and 8 +/- 2.9% of M+ pts overall; PF as the only site of relapse also correlated with M-stage (p = 0.019) and was seen in 6 +/- 2.5 and 0% of M0 and M+ pts, respectively, at 5 years. Relapse in the spine and/or cerebrospinal fluid (CSF) at initial recurrence was correlated with M-stage (p < 0.002), with 5-year cumulative incidences of 14 +/- 3.7%, 26 +/- 8.2%, 40 +/- 15%, and 40 +/- 7.7% for M0, M1, M2, and M3 pts, respectively. Isolated spine/CSF recurrence correlated with M-stage (p = 0.034) and occurred in 2 +/- 1.5% of M0 and 9 +/- 3.2% of M+ pts by 5 years. The median time to relapse for pts who failed was 1.2 years (range 0.2-5.3). Ninety percent of all relapses occurred by 3 years. CONCLUSIONS: Original sites of disease are at the highest risk for relapse, but the entire neuraxis remains at significant risk, despite combined-modality treatment. M-Stage was prognostic for spine/CSF relapse as well as PFS and may be an important tool in guiding therapy. A more aggressive approach to local control in the neuraxis is warranted, especially in M+ patients.

Adolescent↗
PubMed1997

The RAD52 epistasis group in mammalian double strand break repair.

The S. cerevisiae RAD52 epistasis group gene products mediate DNA double strand break repair and recombination. These proteins and their modes of action have been extensively characterized. The existence of highly conserved mammalian RAD52 epistasis group homologues suggests that information regarding the functions and mechanisms of double strand break repair proteins in yeast may be applicable to mammalian recombinational DNA repair. Herein, we provide an overview of the S. cerevisiae RAD52 epistasis group and describe the characterization of the five mammalian RAD52 epistasis group homologues identified to date. In the context of their expression patterns and other functional analyses, we discuss potential roles for these proteins in mammalian recombinational DNA repair and specialized recombination events such as V(D)J recombination.

Cell Division↗
PubMedDate not supplied

Finite element analysis of a Gamma nail within a fractured femur.

Failures of Gamma nails which treat unstable femoral fractures have been reported. In this paper, a finite element model to include a Gamma nail within a fractured femur was used to investigate the stresses in the Gamma nail. The effects for different types of fracture were investigated. The results show that its use for subtrochanteric fractures will cause higher stresses at the lag screw and upper distal screw insertion holes in the nail than when used for femur neck fractures.

Bone Nails↗