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PubMed1999

Step-by-step description of a rotary root canal preparation technique.

CLINICAL TECHNIQUE: Since the introduction of nickel-titanium in endodontics, several canal preparation techniques involving the use of rotary instruments have become popular. Such engine-driven rotary instruments rotate between 150 and 2000 r.p.m. and may be high or low torque orientated. This paper describes one such engine-driven system called the ProFile technique. The instruments are of a different specification to that used for conventional endodontic files and reamers. This paper describes a technique employed by the Division of Endodontology, Zurich Dental School, in a step-by-step procedure using primarily photographs of radiographs. The intention is to give any interested clinician a better idea of the technique using radiographs taken from both the buccolingual (clinical) perspective and the mesiodistal projection. Basically, the technique involves preparing the coronal portion of the root canal using Gates-Glidden burs and the ProFile instruments. Only when any constricting coronal parts of the canals have been removed is the working length established using conventional files. Finally, the apical part of the canal is prepared using only the ProFile instruments. Three clinical cases are also briefly described, in order to illustrate the potential of the technique in cases treated generally by clinicians.

Dental High-Speed Technique↗
PubMed2003

Evidence for male-biased effective sex ratio and recent step-by-step colonization in the bivalve Pinctada mazatlanica.

This paper presents a comparison of the geographical distribution of genetic variability at mitochondrial and nuclear loci among pearl oyster populations from the tropical American Pacific coast (Pinctada mazatlanica). Surprisingly, both mitochondrial and nuclear gene variability decreased regularly from north to south of the studied area, which, altogether with a significant correlation between genetic and geographical distances for mtDNA, suggests a recent colonization or re-colonization of the southern areas. However, the loss of diversity between north and south was much more important for mitochondrial than for nuclear DNA, and this did not translate into measurable fixation index at nuclear loci (theta = 0.03, n.s.), contrary to the mitochondrial data (theta = 0.18*). Smaller effective size of mtDNA accentuated by a strong male-biased effective sex ratio and step-by-step colonization from northern areas can explain this discrepancy among natural populations of this protandric species.

Animals↗
PubMed2006

Computed tomography angiography and computed tomography perfusion in ischemic stroke: A step-by-step approach to image acquisition and three-dimensional postprocessing.

Recent technical advances in both image acquisition and postprocessing have enabled computed tomography angiography (CTA) with computed tomography perfusion to become front-line tools for acute stroke evaluation in many institutions. This article provides a step-by-step approach to utilizing these technologies, particularly in the rapid triage of appropriate stroke patients to reperfusion therapies. The specific contrast injection, image acquisition, and 3D postprocessing protocols for high-quality CTA, currently in use at our institution, are delineated. An important point of emphasis is how preliminary angiographic and cerebral perfusion observations can be made immediately at the scanner to expedite emergent therapy. Also explored is the manner in which a dedicated 3D lab can support a high clinical volume, including a large percentage of emergent studies. An accurate yet time-efficient approach for the neuroradiologist to integrate 3D interpretation with CTA source data review is offered. Several important imaging and interpretive pitfalls in stroke CTA are illustrated.

Angiography↗
PubMed1997

The anti-inflammatory drug sodium salicylate inhibits nitric oxide formation induced by interleukin-1beta at a translational step, but not at a transcriptional step, in hepatocytes.

Recent evidence suggests that nitric oxide (NO) mediates cellular injury under the pathological conditions such as endotoxemia in the liver of rats. Regulation of NO production is crucial for improving the hepatic dysfunction. We have previously reported that, in cultured rat hepatocytes, a single cytokine interleukin-1beta (IL-1beta) stimulated a release of nitrite, an oxidation product of NO, into culture medium dose- and time-dependently. The objective of this study was to investigate an ability of the anti-inflammatory drug NaSA to affect the production of NO in hepatocytes. IL-1beta increased levels of inducible NO synthase (iNOS) messenger RNA (mRNA) with a maximal effect at 8 hours in primary cultures of rat hepatocytes. Nuclear factor-kappaB (NF-kappaB), that is an important nuclear factor protein in iNOS gene transcription in response to inflammatory mediators, also appeared in the nuclear fraction of hepatocytes 1 hour after addition of IL-1beta. Sodium salicylate markedly inhibited the NO formation induced by IL-1beta, but did not affect NF-kappaB activation and iNOS mRNA induction. Western blot analysis revealed that sodium salicylate (NaSA) blocked a step of iNOS protein synthesis. These findings indicate that NaSA may reduce hepatic injury by preventing the induction of NO formation in response to IL-1beta at the posttranscriptional step.

Animals↗
PubMed2002

Initial and late treatment effects of headgear-Herbst appliance with mandibular step-by-step advancement.

The aim of this study was to investigate the effects of the headgear-Herbst appliance with mandibular step-by-step advancement followed by retention with the headgear activator. The sample comprised 22 consecutively treated patients (13.2 +/- 1.5 years old) and 31 matched controls (12.6 +/- 1.3 years old). Lateral cephalograms were obtained at the beginning of treatment, after 6 months (at completion of the initial phase), after 12 months of active treatment (at the end of the late phase), and after 18 months (at the end of retention). The results showed that the skeletal effects over 12 months of treatment were restrained maxillary growth, enhanced mandibular growth, and reduced increase in lower facial height. The restraint effect on the maxilla was significant in both the initial and late phases; the enhanced growth of the mandible was significant during the initial phase only; and the height of the lower face was affected during the late phase only. During retention with the headgear activator, the jaw base relationship was maintained, and the effect on the lower facial height was reinforced. A small relapse of the overjet and molar relationship was the result of dental changes only. During 18 months of active treatment and retention, the overjet correction was the result of 70% skeletal changes. The headgear-Herbst appliance is an effective orthopedic device, and the effect on the maxilla seems to increase with the length of treatment, but the pattern was reversed for the mandible.

Adolescent↗
PubMed2001

Tips and step-by-step protocol for the optimization of important factors affecting cellular enzyme-linked immunosorbent assay (CELISA).

CELISA, or cellular enzyme-linked immunosorbent assay, is a powerful and easy to use technique to study cell surface antigens under different stimulations. Nevertheless, some factors must be discussed and optimized prior to reaching a reproducible CELISA. These include the choice of cell density, fixative agent, blocking agent, culture medium, optimal antibody dilutions, and incubation time. In this paper, we first present a short review of some references devoted to CELISA by means of a comparison of these parameters, followed by their description. Then, we describe and study these different parameters using practical examples comparing TNF-induced ICAM-1 expression as an end point, on HBL melanoma and HUVEC. These cell lines were also chosen because they differ in their ability to grow as discontinuous and continuous layers, respectively. Furthermore, we designed a comprehensive flow chart, as well as a complete step-by-step protocol for CELISA optimization.

Antigens, Surface↗
PubMed2001

A variable fluence step clustering and segmentation algorithm for step and shoot IMRT.

A step and shoot sequencer was developed that can be integrated into an IMRT optimization algorithm. The method uses non-uniform fluence steps and is adopted to the constraints of an MLC. It consists of a clustering, a smoothing and a segmentation routine. The performance of the algorithm is demonstrated for eight mathematical profiles of differing complexity and two optimized profiles of a clinical prostate case. The results in terms of stability, flexibility, speed and conformity fulfil the criteria for the integration into the optimization concept. The performance of the clustering routine is compared with another previously published one (Bortfeld et al 1994 Int. J. Radiat. Oncol. Biol. Ph.vs. 28 723-30) and yields slightly better results in terms of mean and maximum deviation between the optimized and the clustered protile. We discuss the specific attributes of the algorithm concerning its integration into the optimization concept.

Algorithms↗
PubMed2002

Reduction of steps in the preparation of motile sperm for intrauterine insemination does not reduce efficacy of the procedure: simplified one-step swim-up method versus classic swim-up.

BACKGROUND: Intrauterine insemination (IUI) is a valid treatment for infertility with a cumulative pregnancy rate of >40-90% after 3-10 treatment cycles. We studied the efficacy of a simplified method for motile sperm preparation for IUI. METHODS: A prospective clinical trial was performed with 100 couples (male age 33-48 and female 28-37 years) with a 2-8 year history of primary infertility associated with slight oligozoospermia (16/100), oligomenorrhoea (32/100) or unknown (52/100). Motile sperm for IUI were prepared by: (A) the classic World Health Organization self-migration (swim-up) method which includes centrifugation, or (B) a simplified one-step swim-up procedure without centrifugation. Recombinant FSH was used for ovarian stimulation. Depending on the cause of infertility, patients were matched one-to-one at the time of IUI, so that when a total of 100 couples had been treated, 50/100 women received sperm prepared by method A and 50/100 by method B. RESULTS: A statistically significant correlation was found between the percentage motile sperm of the original semen sample and the percentage of motile sperm recovered by method A (r = 0.333, P < 0.01) and B (r = 0.400, P < 0.01). A highly significant correlation (r = 0.997, P < 0.001) was found between the two methods. CONCLUSIONS: The simplified one-step swim-up method was as effective as the classic swim-up method, but the former was easier and more economical.

Adult↗
PubMed1995

US public policy on embryo research: two steps forward, one large step back.

This article gives an overview of the final report of the National Institutes of Health (NIH) Embryo Research Panel, which was issued on September 27, 1994 (NIH, 1994). The report was endorsed unanimously by the Advisory Committee to the Director of the NIH, Harold Varmus, on December 2, 1994. A few hours later, President Clinton (Marshall, 1994) issued a statement announcing that he did 'not believe that federal funds should be used to support the creation of human embryos for research purposes', and that he had directed the NIH not to support such research, which was one of the areas of research recommended for Federal funding by the Panel. At present, Dr Varmus is in the process of considering the Panel's report and shaping guidelines to govern the review and conduct of human embryo research. Any guidelines will be published in the Federal Register for comment at a later date. As a result of changes brought about by Congress in 1993, Federal support for research focused on in-vitro fertilization (IVF) could go forward. This represented the first advance in research freedom in the Federal sector to study approaches to IVF. It will involve the NIH in peer review and scientific activities regarding IVF. Assuming that Dr Varmus develops guidelines to support human embryo research limited to use of 'spare' embryos only and perhaps parthenogenotes, a second step will have been taken. My view about the context and meaning of the President's decision, which is nonetheless a decided step to the rear, appears in the final part.

Fertilization in Vitro↗
PubMed2005

A step-by-step procedure to aid the assessment of intake and doses from measurement data.

The interpretation of bioassay data to assess intakes and doses depends not only on the biokinetic model used but also on the choice of parameter values made by the assessor. Therefore, it is understandable that different assessors will draw different conclusions from the same datasets even if the same models are used. A systematic step-by-step procedure is proposed for the assessment of cases with comprehensive data in which the time of intake is known. The aims are to promote harmonisation of dose assessments and to assist in obtaining the best available assessment of intake and dose from the monitoring data. The procedure is illustrated by means of an example reported recently in the literature. The case which involves a 6 y follow-up of a subject who inhaled (241)Am, is somewhat unusual in that there are comprehensive in vivo measurements, but few excretion data. The rate at which activity is absorbed from lungs to blood can be one of the largest sources of uncertainty in any inhalation assessment, and significantly improved fits to the measurement data were obtained by choosing appropriate values for the relevant parameters. 'The best estimate' of the resulting effective dose in this case was higher by a factor of approximately 2 or 3, respectively, than those obtained assuming ICRP default values for Type M or Type S.

Administration, Inhalation↗
PubMed1993

Background essential to the proper use of results of step 1 and step 2 of the USMLE.

This first of the four-part set of articles published in this issue provides general information and concepts about the Step 1 and Step 2 examinations of the United States Medical Licensing Examination (USMLE) needed for the proper use of these tests' results in three general, related, non-licensure applications: for the evaluation of the examinees' levels of academic achievement, for the evaluation of educational programs the examinees have experienced, and for the selection of examinees into residency programs. Several aspects of the tests are discussed: (1) their original and continuing purpose (which is to assess certain qualifications required for licensure of physicians); (2) their content; (3) their format and the emphases (relative to knowledge or skills testing) that different formats can give, and the concept that the ways the same content areas are formatted in a test will produce different results; (4) test administration, with a discussion of "speeded" versus "power" tests and the organization of test items by difficulty and by (or not by) topic; (5) reliability, with a discussion of standard error and the importance of understanding measurement error in order to discern real differences in scores; (6) scoring, with definition of anchor scores; and (7) interpretation, with discussions of pass/fail criteria in the past, present, and future of the USMLE tests. The authors close by saying that to interpret test performance properly, it is important not only to bear in mind the ideas in the present article but also to carefully review an actual test or at least a representative sample of test questions.

Educational Measurement↗
PubMed2005

Endoscopic examination of the eustachian tube: a step-by-step approach.

OBJECTIVE: The aim of this study was to develop a step-by-step approach for endoscopic examinations of the eustachian tube on awake patients and to report anatomic and functional findings. STUDY DESIGN: Prospective study. SETTING: University hospital. PATIENTS: Convenience sample of seven individuals without a history of ear disease. INTERVENTION: Diagnostic transnasal-transpharyngeal videoendoscopy of the eustachian tube with 30- and 70-degree rigid Hopkins rod endoscopes, 2.5- and 0.8-mm, 0-degree flexible fiber endoscopes performed under local anesthesia in 12 eustachian tubes. MAIN OUTCOME MEASURES: Utility of the various endoscopes for the diagnosis in the different parts of the eustachian tube; quality of vision and the patient's comfort during the procedure. RESULTS: The 2.5-mm flexible endoscope was most useful for examination of the pharyngeal ostium and the cartilaginous lumen of the tube. The isthmus region could only be passed using an 0.8-mm fiberscope. In all cases, it was possible to insert the endoscope into the middle ear cavity. Eleven of the 12 tube examinations showed normal findings. The mobility of the tubal cartilage could be visualized with sufficient quality. In 50% of all examinations, application of local anesthesia via a tube catheter was necessary to make the procedure tolerable. CONCLUSION: The presented approach allows an assessment of both anatomic and functional changes to the eustachian tube in awake patients. The assessment of middle ear structures is limited. To ensure a comfortable and safe procedure, the use of topical anesthesia in a supine position and, in certain cases, additional anesthesia via eustachian tube catheter is recommended.

Adult↗
PubMed2001

Step edge diffusion and step atom detachment in surface evolution: ion erosion of Pt(111).

The temperature dependent morphological evolution of Pt(111) under 1 keV Xe+ normal incidence ion bombardment has been investigated up to 600 monolayers removed. Coarsening of the surface structures during erosion and a qualitative change in roughness evolution between 650 and 700 K are found to be caused by different atomic processes: the former by diffusion of atoms along steps, the latter by the onset of step atom detachment.

Journal Article↗
PubMed2002

Out of the picture: a study of family drawings by children from step-, single-parent, and non-step families.

Investigated the family drawings of 180 children ages 5 to 7 years in various family settings, including stepfather, single-parent, complex stepfamilies, and 2-parent control families. The relations of family type and biological relatedness to omission of family members and grouping of parents were examined. Children from step- and single-parent families were more likely to exclude family members than children from "control" non-step families, and exclusion was predicted from biological relatedness. Children who were biologically related to both resident parents were also more likely to group their parents together. Omission of family members was found to be associated with children's adjustment (specifically more externalizing and internalizing behavior) as reported by teachers and parents. The results indicate that biological relatedness is a salient aspect of very young children's representations of their families. The association between adjustment and exclusion of family members and grouping of parents indicates that family drawings may be useful research and clinical tools, when used in combination with other methods of assessment.

Affective Symptoms↗
PubMed1989

Nucleoside diphosphokinase, an enzyme with step changes in activity during the cell cycle of the fission yeast Schizosaccharomyces pombe. II. Dissociation of the steps from the DNA-division cycle after induction synchronization.

Synchrony was induced in cultures of the mitotic mutant cdc2.33 of Schizosaccharomyces pombe by shifting up an asynchronous culture to the restrictive temperature for a period of 3.5-4.5 h and then shifting down to the permissive temperature. The resulting synchronous divisions had short cycle times, down to 50% of the normal cycle. The oscillatory control of nucleoside diphosphokinase activity was also synchronized by the shift-down and the activity rose in a step pattern. Unlike the situation in the normal cycle, this step pattern was dissociated from the shortened cell cycle and had a longer period and different phase relations. It may be that the normal entrainment or coupling between the cell cycle and the activity control fails if the cell cycle is too short. The period of the activity control (equal to the protein doubling time at the restrictive temperature) appears to be temperature-compensated.

Cell Cycle↗
PubMed1996

Benchmarking reference services: step by step.

This article is a companion to an introductory article on benchmarking published in an earlier issue of Medical Reference Services Quarterly. Librarians interested in benchmarking often ask the following questions: How do I determine what to benchmark; how do I form a benchmarking team; how do I identify benchmarking partners; what's the best way to collect and analyze benchmarking information; and what will I do with the data? Careful planning is a critical success factor of any benchmarking project, and these questions must be answered before embarking on a benchmarking study. This article summarizes the steps necessary to conduct benchmarking research. Relevant examples of each benchmarking step are provided.

Data Collection↗
PubMedDate not supplied

Effects of step-down and step-up heating on the development of thermotolerance in a C3H mammary carcinoma in vivo.

The effects of step-down (SDH) and step-up heating (SUH) on the development of thermotolerance were investigated in a C3H mammary carcinoma in vivo. The endpoint was tumour growth time, i.e. the time for a tumour to reach a volume five times that of the first treatment day. SDH consisted of 44.5 degrees C/5 min followed immediately by 41.0 degrees C/120 min. SUH consisted of the same heat treatments but in reverse sequence. Thermotolerance was detected by subsequent heating at 43.5 degrees C at variable intervals following the primary SDH or SUH. The degree of thermotolerance was quantified by the thermotolerance ratio (TTR) calculated as a ratio between the slope of the dose-response curve for tumours heated at 43.5 degrees C and tumours preheated with either SDH or SUH followed by 43.5 degrees C. Both SDH and SUH induced thermotolerance. However, the maximal degree of thermotolerance and the time interval to reach maximum thermotolerance were different. For SUH maximal thermotolerance was observed at 8 h with a TTR of 3.6. For SUH, thermotolerance peaked at 24-28 h with a TTR of 7.3. In both cases thermotolerance had decayed with a 120 h interval. The SDH priming induced about 2.5 times more heat damage than SUH. The results are therefore in agreement with previous data obtained in the same tumour model by single heating showing that both the degree and the time to reach maximal thermotolerance increases with pretreatment heat damage. In addition, the results indicate that thermotolerance and thermosensitization are independent phenomena.

Animals↗