In ex vivo hip fracture studies femoral pairs are split to create two comparable test groups. When more than two groups are required, or if paired femurs cannot be obtained, group allocation ...according to bone mineral density (BMD) is sometimes performed. In this statistical experiment we explore how this affects experimental results and sample size considerations.
In a hip fracture experiment, nine pairs of human cadaver femurs were tested in a paired study design. The femurs were then re-matched according to BMD, creating two new test groups. Intra-pair variance and paired correlations in fixation stability were calculated. A hypothetical power analysis was then performed to explore the required sample size for the two types of group allocation.
The standard deviation (sd) of the mean paired difference in fixation stability increased from 2 mm in donor pairs to 5 mm in BMD-matched pairs. Intra-pair correlation was 0.953 (Pearson's r) in donor pairs and non-significant at -0.134 (Pearson's r) in BMD-matched pairs. Required sample size to achieve a statistical power of 0.8 increased from ten pairs using donor pairs to 54 pairs using BMD-matched pairs.
BMD cannot be used to create comparable test groups unless sample size is increased substantially and paired statistics are no longer valid. Cite this article: Bone Joint Res 2014;3:317-20.
The hemibiotrophic basidiomycete
Moniliophthora perniciosa causes “witches’ broom disease” in cacao (
Theobroma cacao). During plant infection,
M. perniciosa changes from mono to dikaryotic life ...form, an event which could be triggered by changes in plant nutritional offer and plant defense molecules, i.e., from high to low content of glycerol and hydrogen peroxide. We have recently shown that
in vitro glycerol induces oxidative stress resistance in dikaryotic
M. perniciosa. In order to understand under which conditions in parasite-plant interaction
M. perniciosa changes from intercellular monokaryotic to intracellular dikaryotic growth phase we studied the role of glycerol on mutagen-induced oxidative stress resistance of basidiospores and monokaryotic hyphae; we also studied the role of H
2O
2 as a signaling molecule for
in vitro dikaryotization and whether changes in nutritional offer by the plant could be compensated by inducible fungal autophagy. Mono-/dikaryotic glycerol or glucose-grown cells and basidiospores were exposed to the oxidative stress-inducing mutagens H
2O
2 and Paraquat as well as to pre-dominantly DNA damaging 4-nitroquinoline-1-oxide and UVC irradiation. Basidiospores showed highest resistance to all treatments and glycerol-grown monokaryotic hyphae were more resistant than dikaryotic hyphae. Monokaryotic cells exposed to 1
μM of H
2O
2 in glycerol-media induced formation of clamp connections within 2
days while 1
mM H
2O
2 did not within a week in the same medium; no clamp connections were formed in H
2O
2-containing glucose media within a week. Lower concentrations of H
2O
2 and glycerol, when occurring in parallel, are shown to be two signals for dikaryotization
in vitro and may be also during the course of infection. Q-PCR studies of glycerol-grown dikaryotic cells exposed to oxidative stress (10
mM H
2O
2) showed high expression of Mp
SOD2 and transient induction of ABC cytoplasmic membrane transporter gene Mp
YOR1 and autophagy-related gene Mp
ATG8. Expression of a second ABC transporter gene Mp
SNQ2 was 14-fold induced after H
2O
2 exposure in glucose as compared to glycerol-grown hyphae while Mp
YOR1 did not show strong variation of expression under similar conditions. Glucose-grown dikaryotic cells showed elevated expression of Mp
ATG8, especially after exposure to H
2O
2 and 4-nitroquinoline-1-oxide. During different stages preceding basidiocarp formation Mp
ATG8 and the two catalase-encoding genes Mp
CTA1 and Mp
CTT1 were expressed continuously. We have compiled our results and literature data in a model graph, which compares the
in vitro and
in planta development and differentiation of
M. perniciosa with the help of physiological and morphological landmarks.
To determine whether patients with glaucoma and epiretinal membrane (ERM) use a greater proportion of prostaglandin analogues (PA) than a control group of patients with glaucoma without ERM.
A ...retrospective study of cases and controls was conducted in order to determine whether patients with glaucoma and ERM used a greater proportion of PA than a control group of patients with glaucoma without ERM.
The diagnosis of de ERM was made by clinical examination and optical coherence tomography.
The mean age of the cases was 77 years (SD: 8.68; 95% CI: 74.3–79.4), compared to the controls with 63 years (SD: 16.6; 95% CI: 70.1–78.5). The cases included 50% (n=26) men and 50% women (n=26), whereas in the controls 25.4% (n=16) of the cases were men and 74.6% (n=47) women. PA treatment was used in 59.6% (n=31) and 60.3% (n=38) of the cases and controls, respectively. There was no statistically significant difference in PA use between the 2groups (p=0.939).
In this study, an association between the use of AP and the development of ERM could not be demonstrated.
Evaluar la posible asociación entre el uso de análogos de prostaglandinas (AP) y el desarrollo de membrana epirretinal (MER) en pacientes con glaucoma.
Mediante el método comparativo se realizó un diseño retrospectivo de casos y controles. Se compararon pacientes que presentaban glaucoma y, a su vez, MER y que utilizaban una mayor proporción de AP con un grupo control de pacientes que presentaban glaucoma pero sin MER. El diagnóstico de MER ha sido realizado mediante un examen clínico y un estudio de tomografía de coherencia óptica.
La edad media de los casos ha sido de 77 años, con DE de 8,68 (IC 95%: 74,3-79,4) y la de los controles de 63 años, con DE de 16,6 (IC 95%: 70,1-78,5). El 50% de los casos (n = 26) estaba compuesto por hombres y el otro 50% eran mujeres (n = 26), mientras que para los controles el 25,4% eran hombres (n = 16) y el 74,6% eran mujeres (n = 47). El 59,6% de los casos (n = 31) y el 60,3% de los controles (n = 38) fueron tratados con AP. No se ha observado ninguna diferencia de colocación de AP entre ambos grupos (p=0,939).
En este trabajo no hemos podido demostrar si existe asociación entre el uso de AP y el desarrollo de MER.
Ribonucleotide reductase (RNR) of the yeast Saccharomyces cerevisiae is a tetrameric protein complex, consisting of two large and two small subunits. The small subunits Y2 and Y4 form a heterodimer ...and are encoded by yeast genes RNR2 and RNR4, respectively. Loss of Y4 in yeast mutant rnr4Delta can be compensated for by up-regulated expression of Y2, and the formation of a small subunit Y2Y2 homodimer that allows for a partially functional RNR. However, rnr4Delta mutants exhibit slower growth than wild-type (WT) cells and are sensitive to many mutagens, amongst them UVC and photo-activated mono- and bi-functional psoralens. Cells of the haploid rnr4Delta mutant also show a 3- to 4-fold higher sensitivity to the oxidative stress-inducing chemical stannous chloride than those of the isogenic WT. Both strains acquired increased resistance to SnCl2 with age of culture, i.e., 24-h cultures were more sensitive than cells grown for 2, 3, 4, and 5 days in liquid culture. However, the sensitivity factor of three to four (WT/mutant) did not change significantly. Cultures of the rnr4Delta mutant in stationary phase of growth always showed higher frequency of budding cells (budding index around 0.5) than those of the corresponding WT (budding index <0.1), pointing to a delay of mitosis/cytokinesis.
Although first-generation fuel ethanol is produced in Brazil from sugarcane-based raw materials with high efficiency, there is still little knowledge about the microbiology, the biochemistry and the ...molecular mechanisms prevalent in the non-aseptic fermentation environment. Learning-by-doing has hitherto been the strategy to improve the process so far, with further improvements requiring breakthrough technologies. Performing experiments at an industrial scale are often expensive, complicated to set up and difficult to reproduce. Thus, developing an appropriate scaled down system for this process has become a necessity. In this paper, we present the design and demonstration of a simple and effective laboratory-scale system mimicking the industrial process used for first generation (1G) fuel ethanol production in the Brazilian sugarcane mills. We benchmarked this system via the superior phenotype of the
Saccharomyces cerevisiae
PE-2 strain, compared to other strains from the same species: S288c, baker’s yeast, and CEN.PK113-7D. We trust that such a system can be easily implemented in different laboratories worldwide, and will allow a better understanding of the
S. cerevisiae
strains that can persist and dominate in this industrial, non-aseptic and peculiar environment.
Update
This article was updated on September 4, 2020, because of a previous error. On page 1211, in the author affiliation section, “W.L. Walter, MBBS, PhD
3
” now reads “W.L. Walter, MBBS, PhD
3,4
...,” the affiliation for Dr. Van Onsem that had read “
3
Specialist Orthopedic Group, The Mater Clinic, North Sydney, New South Wales, Australia” now reads “
3
Royal North Shore Hospital, St. Leonards, New South Wales, Australia,” and the affiliation for Dr. Walter that had read “
3
Specialist Orthopedic Group, The Mater Clinic, North Sydney, New South Wales, Australia” now reads “
3
Royal North Shore Hospital, St. Leonards, New South Wales, Australia” and “
4
University of Sydney, Sydney, New South Wales, Australia.”
An erratum has been published: J Bone Joint Surg Am. 2020 Oct 7;102(19):e113
» As we resume elective surgical procedures, it is important to understand what practices and protocols should be altered or implemented in order to minimize the risk of pathogen transfer during the severe acute respiratory syndrome (SARS)-CoV-2 pandemic.
» Each hospital and health system should consider their unique situation in terms of SARS-CoV-2 prevalence, staffing capabilities, personal protection equipment supply, and so on when determining how and when to implement these recommendations.
» All patients should be screened for SARS-CoV-2 by means of a thorough history and physical examination, as well as reverse transcription-polymerase chain reaction (RT-PCR) testing whenever possible, prior to undergoing elective surgery.
» Patients who are currently infected with coronavirus disease 2019 (COVID-19) should not undergo elective surgery.
» These guidelines are based on the available scientific evidence, albeit scant. The recommendations have been reviewed and voted on by the expert delegates who produced this document.
Photovoltaic (PV) system capacity penetration, or simply "penetration," is often defined as the rated power output of the aggregate PV systems on a distribution circuit segment divided by the peak ...load of that circuit segment. Industry experts agree that a single value defining high penetration is not universally applicable. However, it is generally agreed that a conservative value to designate high penetration is the condition when the ratio of aggregate PV systems ratings to peak load exceeds 15%. This case study illustrates the case of a distribution feeder which is able to accommodate a traditional capacity penetration level of 47%, and perhaps more. New maximum penetration levels need to be defined and verified and enhanced definitions for penetration on a distribution circuit need to be developed. The new penetration definitions and studies will help utility engineers, system developers, and regulatory agencies better agree what levels of PV deployment can be attained without jeopardizing the reliability and power quality of a circuit.
Resistance to stannous chloride (SnCl(2)) of the yeast Saccharomyces cerevisiae is a product of several metabolic pathways of this unicellular eukaryote. Sensitivity testing of different null mutants ...of yeast to SnCl(2) revealed that DNA repair contributes to resistance, mainly via recombinational (Rad52p) and error-prone (Rev3p) steps. Independently, the membrane transporter Atr1p/Snq1p (facilitated transport) contributed significantly to Sn(2+)-resistance whereas absence of ABC export permease Snq2p did not enhance sensitivity. Sensitivity of the superoxide dismutase mutants sod1 and sod2 revealed the importance of these anti-oxidative defence enzymes against Sn(2+)-imposed DNA damage while a catalase-deficient mutant (ctt1) showed wild type (WT) resistance. Lack of transcription factor Yap1, responsible for the oxidative stress response in yeast, led to 3-fold increase in Sn(2+)-sensitivity. While loss of mitochondrial DNA did not change the Sn(2+)-resistance phenotype in any yeast strain, cells with defect cytochrome c oxidase (CcO mutants) showed gradually enhanced sensitivities to Sn(2+) and different spontaneous mutation rates. Highest sensitivity to Sn(2+) was observed when yeast was in exponential growth phase under glucose repression. During diauxic shift (release from glucose repression) Sn(2+)-resistance increased several hundred-fold and fully respiring and resting cells were sensitive only at more than 1000-fold exposure dose, i.e. they survived better at 25 mM than exponentially growing cells at 25 microM Sn(2+). This phenomenon was observed not only in WT but also in already Sn(2+)-sensitive rad52 as well as in sod1, sod2 and CcO mutant strains. The impact of metabolic steps in contribution to Sn(2+)-resistance had the following ranking: Resting WT cells > membrane transporter Snq1p > superoxide dismutases > transcription factor Yap1p >or= DNA repair >> exponentially growing WT cells.
»
As we resume elective surgical procedures, it is important to understand what practices and protocols should be altered or implemented in order to minimize the risk of pathogen transfer during the ...severe acute respiratory syndrome (SARS)-CoV-2 pandemic.
»
Each hospital and health system should consider their unique situation in terms of SARS-CoV-2 prevalence, staffing capabilities, personal protection equipment supply, and so on when determining how and when to implement these recommendations.
»
All patients should be screened for SARS-CoV-2 by means of a thorough history and physical examination, as well as reverse transcription-polymerase chain reaction (RT-PCR) testing whenever possible, prior to undergoing elective surgery.
»
Patients who are currently infected with coronavirus disease 2019 (COVID-19) should not undergo elective surgery.
»
These guidelines are based on the available scientific evidence, albeit scant. The recommendations have been reviewed and voted on by the expert delegates who produced this document.
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