A lower threshold for revision of aseptic unicompartmental vs total knee arthroplasty.

AIMS: It has been hypothesized that a unicompartmental knee arthroplasty (UKA) is more likely to be revised than a total knee arthroplasty (TKA) because conversion surgery to a primary TKA is a less complicated procedure. The purpose of this study was to determine if there is a lower threshold for revising a UKA compared with TKA based on Oxford Knee Scores (OKSs) and range of movement (ROM) at the time of revision. METHODS: We retrospectively reviewed 619 aseptic revision cases performed between December 1998 and October 2018. This included 138 UKAs that underwent conversion to TKA and 481 initial TKA revisions. Age, body mass index (BMI), time in situ, OKS, and ROM were available for all patients. RESULTS: There were no differences between the two groups based on demographics or time to revision. The top reasons for aseptic TKA revision were loosening in 212 (44%), instability in 88 (18%), and wear in 69 (14%). UKA revision diagnoses were primarily for loosening in 50 (36%), progression of osteoarthritis (OA) in 50 (36%), and wear in 17 (12%). Out of a maximum 48 points, the mean OKS of the UKAs before revision was 23 (SD 9.3), which was significantly higher than the TKAs at 19.2 (SD 9.8; p < 0.001). UKA patients scored statistically better on nine of the 12 individual OKS questions. The UKA cases also had a larger pre-revision mean ROM (114°, SD 14.3°) than TKAs (98°, SD 25°) ; p < 0.001). CONCLUSION: At revision, the mean UKA OKSs and ROM were significantly better than those of TKA cases. This study suggests that at our institution there is a difference in preoperative OKS between UKA and TKA at the time of revision, demonstrating a revision bias. Cite this article: Bone Joint J 2020;102-B(6 Supple A):91-95.

Radiation risks from exposure to chest computed tomography.

Since 1972, when the first clinical computed tomography (CT) scanner was installed, amazing advances in CT technology have spurned its rapid growth and increasing utilization. Although CT scans are often performed for clinically valid indications that enable proper medical decision-making, the introduction of some protocols has outpaced the scientific data supporting their appropriateness. Considering the growing volume of CT scans performed and the appurtenant risks of radiation exposure, any exposure of patients to radiation for unnecessary or undocumented indications is worrisome. In this paper, the radiation risks associated with chest CT in 3 specific scenarios are discussed: (1) lung cancer screening, for which scientific data demonstrating a reduction in lung cancer mortality is lacking; (2) CT coronary artery angiography, for which the peer reviewed scientific literature is in evolution as its clinical utility is defined and expanded; and (3) CT pulmonary angiography, which is now widely utilized as the imaging modality of choice in the diagnosis of pulmonary emboli. The risks and benefits of these studies will be reviewed in light of the population radiation burden and the appropriateness of each examination.

Transcriptional repression of WEE1 by Kruppel-like factor 2 is involved in DNA damage-induced apoptosis.

Human Kruppel-like factor 2 (KLF2) is a Cys(2)/His(2) zinc-finger-containing transcriptional factor, which is involved in multiple cellular pathways. Utilizing gene expression profiling to identify aberrantly expressed genes in ovarian cancer, we found that KLF2 was significantly and specifically downregulated in ovarian tumors. After reintroducing KLF2 into ovarian cancer cell lines, we observed decreased cell growth and increased sensitivity to DNA damage-induced apoptosis. Analysis of genes that could be potential targets of KLF2 revealed that KLF2 negatively regulated WEE1 expression. WEE1 encodes a tyrosine kinase that regulates the G2/M cell cycle transition. Expression of KLF2 markedly repressed the transcription of WEE1 by directly binding to an SP1/CPBP motif located between -252 bp and the start codon of the WEE1 promoter. Both activation and zinc-finger domains of KLF2 were required for this suppression of Wee1 expression. In addition, we demonstrated that Wee1 expression prevents cancer cells from undergoing apoptosis in response to DNA damage; however, this resistance was abolished by coexpression of KLF2, which inhibits WEE1 transcription. Thus, the level of WEE1 is regulated by KLF2 and enhanced KLF2 expression sensitizes cells to DNA damage-induced apoptosis.

Zero-resistance states induced by electromagnetic-wave excitation in GaAs/AlGaAs heterostructures.

The observation of vanishing electrical resistance in condensed matter has led to the discovery of new phenomena such as, for example, superconductivity, where a zero-resistance state can be detected in a metal below a transition temperature T(c) (ref. 1). More recently, quantum Hall effects were discovered from investigations of zero-resistance states at low temperatures and high magnetic fields in two-dimensional electron systems (2DESs). In quantum Hall systems and superconductors, zero-resistance states often coincide with the appearance of a gap in the energy spectrum. Here we report the observation of zero-resistance states and energy gaps in a surprising setting: ultrahigh-mobility GaAs/AlGaAs heterostructures that contain a 2DES exhibit vanishing diagonal resistance without Hall resistance quantization at low temperatures and low magnetic fields when the specimen is subjected to electromagnetic wave excitation. Zero-resistance-states occur about magnetic fields B = 4/5 Bf and B = 4/9 Bf, where Bf = 2pifm*/e,m* is the electron mass, e is the electron charge, and f is the electromagnetic-wave frequency. Activated transport measurements on the resistance minima also indicate an energy gap at the Fermi level. The results suggest an unexpected radiation-induced, electronic-state-transition in the GaAs/AlGaAs 2DES.