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Biochimie 1977Since Edman's first publication in 1950, the stepwise degradation of proteins and peptides is universally performed by protein chemists. We extensively reviewed the... (Comparative Study)
Comparative Study Review
Since Edman's first publication in 1950, the stepwise degradation of proteins and peptides is universally performed by protein chemists. We extensively reviewed the different manual degradations. We take two examples of manual degradation: a semi-micromethod and a micromethod in order to illustrate the evolution of manual degradation. The "dansyl-Edman" procedure proposed by Hartley in 1963 completes the manual N-terminal determination of peptides. We describe the different procedures of identification of PTH-amino acids: paper chromatography, thin layer chromatography, gas chromatography and liquid chromatography under high pressure and various modified Edman degradation procedures. Possibilities and limits of the liquid phase Sequenator of Edman reported in 1967 and the solid phase Sequencer of Laursen reported in 1971 are also considered in detail.
Topics: Amino Acids; Autoanalysis; Dansyl Compounds; Methods; Microchemistry; Peptides; Proteins
PubMed: 336101
DOI: 10.1016/s0300-9084(77)80166-1 -
Statistical Methods in Medical Research Feb 2015Medical imaging serves many roles in patient care and the drug approval process, including assessing treatment response and guiding treatment decisions. These roles... (Review)
Review
Medical imaging serves many roles in patient care and the drug approval process, including assessing treatment response and guiding treatment decisions. These roles often involve a quantitative imaging biomarker, an objectively measured characteristic of the underlying anatomic structure or biochemical process derived from medical images. Before a quantitative imaging biomarker is accepted for use in such roles, the imaging procedure to acquire it must undergo evaluation of its technical performance, which entails assessment of performance metrics such as repeatability and reproducibility of the quantitative imaging biomarker. Ideally, this evaluation will involve quantitative summaries of results from multiple studies to overcome limitations due to the typically small sample sizes of technical performance studies and/or to include a broader range of clinical settings and patient populations. This paper is a review of meta-analysis procedures for such an evaluation, including identification of suitable studies, statistical methodology to evaluate and summarize the performance metrics, and complete and transparent reporting of the results. This review addresses challenges typical of meta-analyses of technical performance, particularly small study sizes, which often causes violations of assumptions underlying standard meta-analysis techniques. Alternative approaches to address these difficulties are also presented; simulation studies indicate that they outperform standard techniques when some studies are small. The meta-analysis procedures presented are also applied to actual [18F]-fluorodeoxyglucose positron emission tomography (FDG-PET) test-retest repeatability data for illustrative purposes.
Topics: Biomarkers; Diagnostic Imaging; Guidelines as Topic; Humans; Meta-Analysis as Topic; Reproducibility of Results; Research Design; Statistics as Topic
PubMed: 24872353
DOI: 10.1177/0962280214537394 -
Obstetrics and Gynecology Aug 2016The primary goal of sonohysterography is to visualize the endometrial cavity in more detail than is possible with routine transvaginal ultrasonography. Sonohysterography...
The primary goal of sonohysterography is to visualize the endometrial cavity in more detail than is possible with routine transvaginal ultrasonography. Sonohysterography also can be used to assess tubal patency. The indications for sonohysterography include, but are not limited to, evaluation of the following: abnormal uterine bleeding; uterine cavity, especially with regard to uterine leiomyomata, polyps, and synechiae; abnormalities detected on transvaginal ultrasonography, including focal or diffuse endometrial or intracavitary abnormalities; congenital abnormalities of the uterus; infertility; recurrent pregnancy loss; and suboptimal visualization of the endometrium on transvaginal ultrasonography. Sonohysterography should not be performed in a woman who is pregnant or who could be pregnant. Credentialing obstetrician-gynecologists to perform or supervise diagnostic sonohysterography should be based on education, training, experience, and demonstrated competence in performing and interpreting trans-vaginal ultrasonography and sonohysterography. The obstetrician-gynecologist should be skilled in the transcervical placement of catheters. The sonohysterography procedure, including benefits and risks, should be explained fully to the patient before the procedure is performed.
Topics: Contraindications; Documentation; Endosonography; Female; Humans; Patient Selection; Physician's Role; Technology Assessment, Biomedical; Uterus
PubMed: 27454735
DOI: 10.1097/AOG.0000000000001588 -
Statistics in Medicine Dec 2023In randomized trials, comparability of the treatment groups is ensured through allocation of treatments using a mechanism that involves some random element, thus...
In randomized trials, comparability of the treatment groups is ensured through allocation of treatments using a mechanism that involves some random element, thus controlling for confounding of the treatment effect. Completely random allocation ensures comparability between the treatment groups for all known and unknown prognostic factors. For a specific trial, however, imbalances in prognostic factors among the treatment groups may occur. Although accidental bias can be avoided in the presence of such imbalances by stratifying the analysis, most trialists, regulatory agencies, and other stakeholders prefer a balanced distribution of prognostic factors across the treatment groups. Some procedures attempt to achieve balance in baseline covariates, by stratifying the allocation for these covariates, or by dynamically adapting the allocation using covariate information during the trial (covariate-adaptive procedures). In this Tutorial, the performance of minimization, a popular covariate-adaptive procedure, is compared with two other commonly used procedures, completely random allocation and stratified blocked designs. Using individual patient data of 2 clinical trials (in advanced ovarian cancer and age-related macular degeneration), the procedures are compared in terms of operating characteristics (using asymptotic and randomization tests), predictability of treatment allocation, and achieved balance. Fifty actual trials of various sizes that applied minimization for treatment allocation are used to investigate the achieved balance. Implementation issues of minimization are described. Minimization procedures are useful in all trials but especially when (1) many major prognostic factors are known, (2) many centers of different sizes accrue patients, or (3) the trial sample size is moderate.
Topics: Humans; Bias; Randomized Controlled Trials as Topic; Research Design; Sample Size
PubMed: 37867447
DOI: 10.1002/sim.9916 -
Cutis Dec 2012Hair transplantation is a purely dermatologic surgical procedure that dermatologists should be able to perform in appropriate candidates with hair loss. Hair... (Review)
Review
Hair transplantation is a purely dermatologic surgical procedure that dermatologists should be able to perform in appropriate candidates with hair loss. Hair transplantation techniques performed in the 1960s through the 1990s utilized large grafts that created an unfortunate public image of unnatural-appearing transplanted hair. Over the last 15 years, hair transplantation has been performed using follicular units to create consistently natural-looking transplanted hair in both men and women. This article provides an overview of candidate selection and state-of-the-art techniques for performing hair transplantation.
Topics: Alopecia; Hair Follicle; Humans; Patient Selection; Scalp; Tissue and Organ Harvesting
PubMed: 23409484
DOI: No ID Found -
Stroke Sep 2019Background and Purpose- Radial artery catheterization is an alternate route of access that has started to gain more widespread use for neuroendovascular procedures, and...
Background and Purpose- Radial artery catheterization is an alternate route of access that has started to gain more widespread use for neuroendovascular procedures, and there have been few studies that describe its safety and efficacy. We present our institution's experience in performing neuroendovascular interventions via a transradial approach, with excellent clinical outcomes and patient satisfaction measures. Methods- We conducted a retrospective analysis and identified 223 patients who underwent 233 consecutive neuroendovascular interventions via radial artery access at our institution. The incidence of perioperative and postprocedural complications was investigated. We identified a subset of 98 patients who have undergone both transradial and transfemoral cerebral angiograms and compared clinical outcomes and patient satisfaction measures between the 2 groups. Results- The overall incidence of complications was low across all procedures performed via transradial access. Peri-procedurally, only 2 patients had symptomatic radial artery spasm, and there were no instances of iatrogenic complications (vessel dissection, stroke, and hemorrhage). In 10 cases (4.3%), the intended procedure could not be completed via a transradial approach, and, thus, femoral artery access had to be pursued instead. Ten patients complained of minor postprocedural complications, although none required therapeutic intervention. The mean procedure time was shorter for diagnostic angiograms performed via transradial versus transfemoral access (18.8±15.8 versus 39.5±31.1 minutes; P=0.025). Patients overall reported shorter recovery times with transradial access, and the majority of patients (94%) would elect to have subsequent procedures performed via this route. Conclusions- Radial artery catheterization is a safe and durable alternative to perform a wide range of neuroendovascular procedures, with a low rate of complications. On the whole, patients prefer transradial compared with transfemoral access.
Topics: Cardiac Catheterization; Cerebral Angiography; Female; Hemorrhage; Humans; Middle Aged; Radial Artery; Retrospective Studies; Stroke; Treatment Outcome
PubMed: 31311466
DOI: 10.1161/STROKEAHA.119.025811 -
Journal of AOAC International 2014This paper reviews the main concepts of experimental design applicable to the optimization of analytical chemistry techniques. The critical steps and tools for... (Review)
Review
This paper reviews the main concepts of experimental design applicable to the optimization of analytical chemistry techniques. The critical steps and tools for screening, including Plackett-Burman, factorial and fractional factorial designs, and response surface methodology such as central composite, Box-Behnken, and Doehlert designs, are discussed. Some useful routines are also presented for performing the procedures.
Topics: Algorithms; Chemistry Techniques, Analytical; Models, Theoretical; Research Design
PubMed: 24672854
DOI: 10.5740/jaoacint.sgeebrahimi1 -
Journal of Biopharmaceutical Statistics 2017Pocock and Simon's minimization method is a very popular covariate-adaptive randomization procedure intended to balance the allocations of two treatments across a set of...
Pocock and Simon's minimization method is a very popular covariate-adaptive randomization procedure intended to balance the allocations of two treatments across a set of covariates without compromising randomness. Additional covariate-adaptive schemes have been proposed in the literature, such as Atkinson's [Formula: see text]-optimum Biased Coin Design and the Covariate-Adaptive Biased Coin Design (CA-BCD), and their properties were analyzed and compared in terms of imbalance and predictability. The aim of this paper is to push forward these comparisons by also taking into account other randomization methods, such as the Permuted Block Design, the Big Stick Design, a generalization of the CA-BCD that can be implemented when the covariate distribution is unknown, and the Covariate-Adaptive Dominant Biased Coin Design, which is a new class of stratified randomization methods that forces the balance increasingly as the joint imbalance grows and improves the degree of randomness as the size of every stratum increases. The performance of covariate-adaptive procedures is strictly related to the considered factors and the number of patients in the trial as well, which makes it hard to find a dominant rule, namely a design that is more balanced and less predictable with respect to other schemes. In general, stratified randomization methods perform very well when the number of strata is small, showing also some dominance structure with respect to the other designs. Nevertheless, the evolution and the performance of stratified designs are strictly related to the random entries of the subjects. Thus, these rules become less efficient in the case of both (i) limited samples and (ii) large number of factors/levels.
Topics: Computer Simulation; Humans; Linear Models; Random Allocation; Research Design
PubMed: 28166466
DOI: 10.1080/10543406.2017.1289944 -
Thoracic Surgery Clinics Nov 2019Failure to recognize a short esophagus during paraesophageal hernia repair can lead to poor functional outcomes and increased recurrence rates. Diagnosis is usually done... (Review)
Review
Failure to recognize a short esophagus during paraesophageal hernia repair can lead to poor functional outcomes and increased recurrence rates. Diagnosis is usually done intraoperatively when less than 2 to 3 cm of esophagus lie in the intraabdominal position. If aggressive esophageal mediastinal mobilization is unable to lengthen the esophagus, the surgeon should perform an esophageal lengthening procedure. A modified Collis gastroplasty is most commonly used and can be performed through a variety of transabdominal or transthoracic approaches. These procedures are safe, durable, and associated with good long-term outcomes. Patient selection and safe surgical technique are key in avoiding complications.
Topics: Esophagus; Fundoplication; Gastroplasty; Hernia, Hiatal; Herniorrhaphy; Humans; Laparoscopy; Mediastinum; Organ Size; Patient Selection
PubMed: 31564395
DOI: 10.1016/j.thorsurg.2019.07.004 -
Burns : Journal of the International... Nov 2010Severe facial burns cause significant deformities that are technically challenging to treat. Conventional treatments almost always result in poor aesthetic and... (Review)
Review
Severe facial burns cause significant deformities that are technically challenging to treat. Conventional treatments almost always result in poor aesthetic and functional outcomes. This is due to the fact that current treatments cover or replace the delicate anatomical facial tissues with autologus grafts and flaps from remote sites. The recent introduction of clinical composite tissue allotransplantation (CTA) that uses healthy facial tissue transplanted from donors to reconstruct the damaged or non-existing facial tissues with original tissues makes it possible to achieve the best possible functional and aesthetic outcomes in these challenging injuries. The techniques required to perform this procedure, while technically challenging, have been developed over many years and are used routinely in reconstructive surgery. The immunosuppressive regimens necessary to prevent transplanted facial tissue from rejecting (tacrolimus/mycophenolate mofetil/steroid) were developed for and have been used successfully in solid organ transplants for many years. The psychosocial and ethical issues associated with this new treatment have some nuances but generally have many similarities with solid organ and more recently hand transplantation, both of which have been performed clinically for 40 and 10+ years respectively. Herein, we will discuss the technical and immunological aspects of facial tissue transplantation. The psychosocial and ethical issues will be discussed separately in another article in this issue.
Topics: Burns; Facial Transplantation; Graft Rejection; Humans; Immunosuppressive Agents; Patient Selection; Plastic Surgery Procedures; Skin Transplantation; Tissue and Organ Procurement; Transplantation, Homologous
PubMed: 20413224
DOI: 10.1016/j.burns.2010.01.011