SEARCH · PubMed Health

Results for “systematics”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 289 records · Page 16Linked to original sources

PubMed2004

Gastrostomy feeding in cerebral palsy: a systematic review.

AIMS: To determine benefits and risks for gastrostomy or jejunostomy feeding compared with oral feeding for children with cerebral palsy. METHODS: Systematic review. SEARCH STRATEGY: electronic databases--Cochrane Library, Medline, Embase, Cinahl, Lilacs, databases of theses, grey literature. INCLUDED: relevant systematic reviews, randomised controlled trials, observational studies, case reports. EXCLUDED: non-systematic reviews and qualitative research. PARTICIPANTS: children with cerebral palsy. INTERVENTION: use of gastrostomy or jejunostomy tube to provide nutrition. OUTCOME: evaluated outcome measures included death, growth, gastro-oesophageal reflux, other complications, psychosocial aspects, and caregiver wellbeing. RESULTS: No relevant systematic reviews or randomised controlled trials were found. Two cohort studies, 15 case series, and eight case reports met the inclusion criteria. Eight studies specifically described percutaneous endoscopic gastrostomy as the intervention. Weight gain resulted from gastrostomy feeding in most cases. There was an approximately fourfold increased risk of death reported in one cohort study for the gastrostomy fed children. Many complications were reported, including potential for increased gastro-oesophageal reflux and fluid aspiration into the lungs. CONCLUSIONS: Benefits associated with gastrostomy or jejunostomy feeding are difficult to assess from the available evidence. Risks of gastrostomy, particularly in relation to surgical complications, have been described but the size of the risk could not be quantified. The finding of a higher death rate for children fed by gastrostomy may merely reflect the greater disability of these compared with orally fed children. Lack of available evidence and the substantial risk of bias in observational studies suggests that a well conducted randomised controlled trial of sufficient size will be needed to answer these problems.

Cerebral Palsy↗

PubMed2004

Manual versus powered toothbrushes: a summary of the Cochrane Oral Health Group's Systematic Review. Part II.

PURPOSE: A systematic review examining the clinical effectiveness of power versus manual toothbrushes was conducted by the Cochrane Collaborations Oral Health Group. Their review examined clinical trials conducted through 2001 and used international standards to identify, access, evaluate, analyze, and report the data. Part I of this series discussed distinguishing characteristics of evidence-based publications, such as systematic reviews, whereas this report provides a summary of the Cochrane Review, its importance to the profession, and discusses the strengths and limitations of systematic reviews. METHODS: Search strategies to identify published clinical trials on power toothbrushes were developed, and manufacturers were contacted for additional published and unpublished information. Trials were selected based on pre-established criteria; including whether they compared power versus manual toothbrushes used a randomized research design tested products in the general population without disabilities, provided data on plaque and gingivitis, and were at least 28 days in length. Six reviewers independently extracted information in duplicate. Indices for plaque and gingivitis levels were expressed as standardized mean differences for data distillation. Data distillation was accomplished using a meta-analysis, with a mean difference between power and manual toothbrushes as the measure of effectiveness. RESULTS: Searches identified 354 trials, of which 29 met inclusion criteria. These trials involved 2.547 participants who provided data for meta-analysis. Results indicated that for both plaque and gingivitis, all types of power toothbrushes worked as well as manual toothbrushes, however only the rotating oscillating toothbrush consistently provided a statistically significant though modest benefit over manual toothbrushes in reducing plaque (7%) and gingivitis (17%). None of the battery powered toothbrush studies met the inclusion criteria. CONCLUSION: The Cochrane systematic review used international standards to examine more than 30 years of published studies. A concern is that only one type of electric toothbrush, the rotating oscillating toothbrush consistently demonstrated a statistically significant benefit over manual toothbrushes, and the majority of studies did not meet the standards for inclusion in moving forward it will be important to conduct methodologically sound studies demonstrating the ability of power toothbrushes to reduce the incidence and prevalence of caries and periodontal disease.

Decision Making↗

PubMed2006

Types of clinical studies. Systematic reviews.

Systematic reviews are analytic instruments that summarize the best available scientific evidence in order to provide evidence-based answers to clinically relevant questions. Meta-analyses are systematic reviews with a quantitative analysis of results. The process of conducting a systematic review is a rigorous and standardized procedure that includes: 1) formulating a clinically relevant question; 2) explicit selection of studies (primary or secondary) to be included in the review; 3) critical appraisal of the relevant evidence; 4) summarizing the evidence; and 5) statistical analysis of the results. In this paper we describe the steps involved in conducting a systematic review of scientific evidence, the methodology, and problems.

Clinical Trials as Topic↗

PubMed1997

The systematic review: an essential element of an evidence based approach to nursing.

Consistent with a move towards evidence based practice, systematic review of research relating to effective health care practices is having an increasing influence on health care decision making at all levels. This paper explains the systematic review as a specific type of literature review, one that contrasts with less rigorous approaches to assessing current best available research evidence. The use of this process to achieve effective nursing practice is discussed in the context of systematic review in medicine and health services in general. It is asserted that, in the 'information age', understanding and being able to assess the quality of systematic reviews is an essential area of nursing research.

Humans↗

PubMed2026

Effectiveness of exercise-based prehabilitation on pre and postoperative outcomes of patients undergoing cardiac surgery-An umbrella review of systematic reviews.

AIMS: Individuals undergoing cardiac surgery are becoming older, frailer, and less mobile. Prehabilitation has shown to improve postoperative outcomes by optimizing preoperative physical function. This umbrella review aims to pool the systematic reviews assessing the effectiveness of exercise-based prehabilitation in cardiac surgery. METHODS AND RESULTS: The review followed the PRIOR checklist. PubMed, Embase, CINAHL, Cochrane library, Scopus, Web of science, ProQuest NAHD, ProQuest HMC, Open Grey and MedNar were searched using relevant keywords from inception to 16th December, 2024. Two reviewers screened and extracted data from the included reviews and assessed primary study overlap with the corrected covered area. Methodological quality of the reviews was evaluated with the A MeaSurement Tool to Assess systematic Reviews-2 scale. Certainty of evidence was assessed using a previously developed criteria for overview of reviews. Six systematic reviews with 30 unique trials and 6705 participants were included. The interventions assessed included breathing exercises, inspiratory muscle training, and exercise training. Prehabilitation reduced length of hospital stay, postoperative pulmonary complications, and clinically improved functional capacity with a very low to moderate certainty of evidence. However, there was uncertainty regarding the effects pertaining to adverse events and quality of life. The methodological quality of all reviews was critically low. The primary trials scored poorly in the domains of selection and detection bias. CONCLUSION: Exercise-based prehabilitation might reduce length of hospital stay and postoperative complications, and improve functional capacity. However, the quality of evidence is poor, and individual discretion is required before implementing them into practice. REGISTRATION: PROSPERO: CRD42023480100.

Humans↗

PubMed2007

Cost-effectiveness of systematic depression treatment among people with diabetes mellitus.

CONTEXT: Depression co-occurring with diabetes mellitus is associated with higher health services costs, suggesting that more effective depression treatment might reduce use of other medical services. OBJECTIVE: To evaluate the incremental cost and cost-effectiveness of a systematic depression treatment program among outpatients with diabetes. DESIGN: Randomized controlled trial comparing systematic depression treatment program with care as usual. SETTING: Primary care clinics of group-model prepaid health plan. PATIENTS: A 2-stage screening process identified 329 adults with diabetes and current depressive disorder. INTERVENTION: Specialized nurses delivered a 12-month, stepped-care depression treatment program beginning with either problem-solving treatment psychotherapy or a structured antidepressant pharmacotherapy program. Subsequent treatment (combining psychotherapy and medication, adjustments to medication, and specialty referral) was adjusted according to clinical response. MAIN OUTCOME MEASURES: Depressive symptoms were assessed by blinded telephone assessments at 3, 6, 12, and 24 months. Health service costs were assessed using health plan accounting records. RESULTS: Over 24 months, patients assigned to the intervention accumulated a mean of 61 additional days free of depression (95% confidence interval [CI], 11 to 82 days) and had outpatient health services costs that averaged $314 less (95% CI, $1007 less to $379 more) compared with patients continuing in usual care. When an additional day free of depression is valued at $10, the net economic benefit of the intervention is $952 per patient treated (95% CI, $244 to $1660). CONCLUSIONS: For adults with diabetes, systematic depression treatment significantly increases time free of depression and appears to have significant economic benefits from the health plan perspective. Depression screening and systematic depression treatment should become routine components of diabetes care.

Ambulatory Care↗

PubMed1998

Methodology and reports of systematic reviews and meta-analyses: a comparison of Cochrane reviews with articles published in paper-based journals.

CONTEXT: Review articles are important sources of information to help guide decisions by clinicians, patients, and other decision makers. Ideally, reviews should include strategies to minimize bias and to maximize precision and be reported so explicitly that any interested reader would be able to replicate them. OBJECTIVE: To compare the methodological and reporting aspects of systematic reviews and meta-analyses published by the Cochrane Collaboration with those published in paper-based journals indexed in MEDLINE. DATA SOURCES: The Cochrane Library, issue 2 of 1995, and a search of MEDLINE restricted to 1995. STUDY SELECTION: All 36 completed reviews published in the Cochrane Database of Systematic Reviews and a randomly selected sample of 39 meta-analyses or systematic reviews published in journals indexed by MEDLINE in 1995. DATA EXTRACTION: Number of authors, trials, and patients; trial sources; inclusion and exclusion criteria; language restrictions; primary outcome; trial quality assessment; heterogeneity testing; and effect estimates. Updating by 1997 was evaluated. RESULTS: Reviews found in MEDLINE included more authors (median, 3 vs 2; P<.001), more trials (median, 13.5 vs 5; P<.001), and more patients (median, 1280 vs 528; P<.001) than Cochrane reviews. More Cochrane reviews, however, included a description of the inclusion and exclusion criteria (35/36 vs 18/39; P<.001) and assessed trial quality (36/36 vs 12/39; P<.001). No Cochrane reviews had language restrictions (0/36 vs 7/39; P<.01). There were no differences in sources of trials, heterogeneity testing, or description of effect estimates. By June 1997, 18 of 36 Cochrane reviews had been updated vs 1 of 39 reviews listed in MEDLINE. CONCLUSIONS: Cochrane reviews appear to have greater methodological rigor and are more frequently updated than systematic reviews or meta-analyses published in paper-based journals.

Meta-Analysis as Topic↗

PubMed2004

Different patterns of duplicate publication: an analysis of articles used in systematic reviews.

CONTEXT: Duplicate publication is publication of an article that overlaps substantially with an article published elsewhere. Patterns of duplication are not well understood. OBJECTIVE: To investigate duplication patterns and propose a decision tree for classification. DATA SOURCES: We searched a comprehensive list of systematic reviews (1989 through August 15, 2002) in anesthesia and analgesia that is accessible on the Internet. We selected published full articles of duplicates that had been identified in these systematic reviews. Abstracts, letters, or book chapters were excluded. STUDY SELECTION AND DATA EXTRACTION: Authors of 56 (40%) of 141 systematic reviews acknowledged identification of duplicates. Duplication patterns were identified independently by all investigators comparing samples and outcomes of pairs of duplicates and main articles. Information on cross-reference, sponsorship, authorship, and publication characteristics was extracted from the articles. DATA SYNTHESIS: The 56 systematic reviews included 1131 main articles (129 337 subjects) and excluded 103 duplicates (12 589 subjects) that originated from 78 main articles. Sixty articles were published twice, 13 three times, 3 four times, and 2 five times. We identified 6 duplication patterns: (1A) identical samples and identical outcomes (21 pairs); (1B) same as 1A but several duplicates assembled (n = 16); (2) identical samples and different outcomes (n = 24); (3A) increasing sample and identical outcomes (n = 11); (3B) decreasing sample and identical outcomes (n = 11); (4) different samples and different outcomes (n = 20). The prevalence of covert duplicate articles (without a cross-reference to the main article) was 5.3% (65/1234). Of the duplicates, 34 (33%) were sponsored by the pharmaceutical industry, and 66 (64%) had authorship that differed partly or completely from the main article. The median journal impact factor was 1.8 (range, 0.1-29.5) for duplicates and 2.0 (range, 0.4-29.5) for main articles (P =.13). The median annual citation rate was 1.7 (range, 0-27) for duplicates and 2.1 (range, 0-31) for main articles (P =.45). The median number of authors was 4 (range, 1-14) for duplicates and 4 (range, 1-15) for corresponding main articles (P =.02). The median delay in publication between main articles and duplicates was 1 year (range, 0-7 years). CONCLUSIONS: Duplication goes beyond simple copying. Six distinct duplication patterns were identified after comparing study samples and outcomes of duplicates and corresponding main articles. Authorship was an unreliable criterion. Duplicates were published in journals with similar impact factors and were cited as frequently as main articles.

Analgesia↗

PubMed2002

Does systematic lymphadenectomy have a benefit on survival of suboptimally debulked patients with stage III ovarian carcinoma? A DEGOG* Study.

BACKGROUND AND OBJECTIVES: The aim of this study was to investigate whether systematic lymphadenectomy is necessary in suboptimally cytoreduced patients with stage III ovarian carcinoma. METHODS: Prognostic significance and the effect on survival of systematic pelvic and para-aortic lymphadenectomy were investigated retrospectively in 61 suboptimally debulked patients with stage III ovarian carcinoma. All patients received platinum-based chemotherapy after surgery; 51 patients had been followed for > or =1 year, or until death. Survival curves were calculated according to the Kaplan-Meier method and were evaluated by log-rank test. RESULTS: Most patients had stage IIIC disease (60.7%), poorly differentiated tumor (45.9%), and serous histological type (59%). Systematic pelvic and para-aortic lymphadenectomy was performed in 29 patients (47.5%). Lymph node metastases were found in 17 (58.6%) patients; the median number of metastatic nodes was 7 (5-10). Lymph node metastasis was significantly higher in patients with residual disease of >2 cm (P < 0.05). Both univariate and multivariate analyses showed that systematic pelvic and para-aortic lymphadenectomy was not a significant prognostic factor (P > 0.05). In lymph node-dissected patients, survival was significantly longer in patients with minimal residual tumor than in those with residual tumor size >2 cm (P = 0.005). CONCLUSIONS: Lymphadenectomy seems not to have an evident prognostic value and a benefit on survival in suboptimally debulked patients with stage III ovarian carcinoma.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed2001

Systematic errors of planar arm movements provide evidence for space categorization effects and interaction of multiple frames of reference.

Healthy humans performed arm movements in a horizontal plane, from an initial position toward remembered targets, while the movement and the targets were projected on a vertical computer monitor. We analyzed the mean error of movement endpoints and we observed two distinct systematic error patterns. The first pattern resulted in the clustering of movement endpoints toward the diagonals of the four quadrants of an imaginary circular area encompassing all target locations (oblique effect). The second pattern resulted in a tendency of movement endpoints to be closer to the body or equivalently lower than the actual target positions on the computer monitor (y-effect). Both these patterns of systematic error increased in magnitude when a time delay was imposed between target presentation and initiation of movement. In addition, the presence of a stable visual cue in the vicinity of some targets imposed a novel pattern of systematic errors, including minimal errors near the cue and a tendency for other movement endpoints within the cue quadrant to err away from the cue location. A pattern of systematic errors similar to the oblique effect has already been reported in the literature and is attributed to the subject's conceptual categorization of space. Given the properties of the errors in the present work, we discuss the possibility that such conceptual effects could be reflected in a broad variety of visuomotor tasks. Our results also provide insight into the problem of reference frames used in the execution of these aiming movements. Thus, the oblique effect could reflect a hand-centered reference frame while the y-effect could reflect a body or eye-centered reference frame. The presence of the stable visual cue may impose an additional cue-centered (allocentric) reference frame.

Adult↗

PubMed2005

Systematic hepatectomy for small hepatocellular carcinoma in Korea.

BACKGROUND/PURPOSE: Systematic hepatectomy for small hepatocellular carcinoma (HCC) is a widely preferred modality, but evidence concerning its benefits is lacking. The aim of this study was to document hepatic resection for small HCC in Korea, and to determine whether patient survival or the pattern of tumor recurrence was influenced by the methods used. METHODS: Ten major hospitals that perform hepatectomy for HCC in Korea were surveyed for surgeons' opinions concerning systematic hepatectomy and current trends in hepatic resection for small HCC. An analysis was also performed of 119 patients who underwent curative hepatectomy for small HCC (size < 5 cm) between January 2000 and December 2002 at Seoul National University Hospital. Seventy-four of these 119 patients underwent anatomical resection (AR) and 45 had a non-anatomical resection (NAR). Recurrence-free survival, recurrence pattern, overall survival rates, and the risk factors for recurrence were analyzed. RESULTS: In the survey, eight of ten surgeons preferred systematic hepatectomy and considered it to aid prognosis. No significant difference was found between the AR and NAR groups in terms of the clinicopathologic findings, except that the presence of underlying hepatic cirrhosis was more prevalent in the NAR group. The postoperative morbidity rate was higher in the NAR group (33.3% vs 27.0%), but this difference was not statistically significant. The respective 1- and 3-year recurrence-free survival rates were 78.1% and 49.7% in the AR group, and 68.9% and 46.5% in the NAR group (P > 0.05). The corresponding 1- and 3-year overall survival rates were 88.8% and 80.8% in the AR group and 91.0% and 71.4% in the NAR group (P > 0.05). CONCLUSIONS: Although systematic hepatectomy seems to be superior to non-anatomical hepatectomy from the oncological and anatomical aspects, this superiority is not reflected by the recurrence patterns or the survival and recurrence rates of the two procedures. Postoperative recurrence appears, rather, to be related to the underlying liver condition.

Adolescent↗

PubMed2002

Exposure to prenatal infections, genetics and the risk of systematic and periodic catatonia.

The meaning of heterogeneity in schizophrenia and the impact of genetic and environmental factors on etiology are a matter of continuous debate in psychiatric research. Different clinical and birth history variables were investigated in a sample of 68 patients with chronic catatonic schizophrenia according to DSM III-R, classified into Leonhard's systematic schizophrenia (n = 32) and periodic catatonia (n = 36). Parental transmission of the disease was evident in 44% of the periodic catatonia cases compared to one case in systematic catatonia (3%; p = 0.0003). In systematic catatonia, 34% of the index cases were exposed to prenatal infections compared to 8% in periodic catatonia (p = 0.008). Using logistic regression analysis exposure to gestational maternal infections predicted diagnosis of systematic catatonia at p = 0.008, and parental psychosis predicted diagnosis of periodic catatonia in the index cases at p = 0.0001. The latter finding is substantiated by the recent mapping of a periodic catatonia-susceptibility locus on chromosome 15q15 with evidence for autosomal dominant transmission. These findings support the hypothesis that distinct schizophrenia phenotypes are based on different etiological mechanisms.

Adult↗

PubMed1990

Connectionism and the problem of systematicity: why Smolensky's solution doesn't work.

In two recent papers, Paul Smolensky responds to a challenge Jerry Fodor and Zenon Pylyshyn posed for connectionist theories of cognition: to explain the existence of systematic relations among cognitive capacities without assuming that mental processes are causally sensitive to the constituent structure of mental representations. Smolensky thinks connectionists can explain systematicity if they avail themselves of "distributed" mental representation. In facts, Smolensky offers two accounts of distributed mental representation, corresponding to his notions of "weak" and "strong" compositional structure. We argue that weak compositional structure is irrelevant to the systematicity problem and of dubious internal coherence. We then argue that strong compositional (tensor product) representations fail to explain systematicity because they fail to exhibit the sort of constituents that can provide domains for structure sensitive mental processes.

Cognition↗

PubMed1994

Systematic errors for saccades to remembered targets: evidence for a dissociation between saccade metrics and activity in the superior colliculus.

Pronounced systematic errors are a consistent feature of saccades to remembered target locations. In an effort to determine their neural basis, we recorded from saccade-related burst neurons (SRBNs) in the superior colliculus and compared the discharges associated with saccades to visual and remembered targets. For all recorded SRBNs, the relationship between discharge rate and saccade metrics differed for saccades to visual and remembered targets; movement fields constructed from saccades to remembered targets were shifted relative to those for visual targets. The shifts of the remembered movement fields were consistent with the direction and magnitude of the systematic errors observed on memory trials. These findings suggest that the superior colliculus is not the source of the systematic errors observed on memory trials. Systematic errors are likely due to the addition or omission of signals downstream from the superior colliculus.

Action Potentials↗

PubMed1988

Systematics of the nematodes that cause ostertagiasis in cattle, sheep and goats in North America.

The systematics of the Ostertagiinae is unsettled with no agreement on how many genera and species are present in cattle and sheep. Ten species of Ostertagiinae are commonly parasitic in cattle and sheep. The males can be identified on the basis of differences in morphology of spicules and genital cones but the females of most species cannot be identified. The species-level systematics have been complicated by the proposal that the ten species are polymorphs of only five species. The systematics at genus level has been complicated by the use of numerous genera for the ten species, at present most commonly Ostertagia, Teladorsagia and Marshallagia. This report (1) describes the current knowledge of the systematics and (2) provides diagnoses of the genera recommended for the ten species. The morphology of the ten species was studied to determine whether characteristics could be found to identify females or to further differentiate the males. Characters studied included the system of longitudinal and surface cuticular ridges (synlophe), the internal morphology of the esophagus and the orientation of rays of the copulatory bursa. The study of species morphology resulted in additional support for the polymorphism proposal. All minor species were found to be identical to their major species in characteristics of the synlophe, esophagus and rays of the copulatory bursa. Two recent classifications of the Ostertagiinae both recommended the use of the genus Teladorsagia for the species T. circumcincta and the two minor species that occur with it, T. trifurcata and T. davtiani. Teladorsagia is characterized by a copulatory bursa in which the five lateral rays are arranged 2-2-1 and a ventral swelling of the genital cone (proconus) is absent. One pair of species, Marshallagia marshalli (major species) and Ostertagia occidentalis (minor species) should be included in the genus Marshallagia. This genus has been characterized by an elongated bursa in which the posterior pair of lateral rays are much longer than the ventral pair. The remaining two pairs of species (O. ostertagi and its minor species O. lyrata, and O. leptospicularis and its minor species O. kolchida) and O. bisonis belong in the genus Ostertagia which is characterized by a 2-1-2 arrangement of the five lateral rays of the copulatory bursa and the presence of a proconus.

Animals↗

PubMed1983

Systematic epidemiologic theory: conceptual foundations and axiomatic elements.

Since the initial epidemiologic confrontations of chronic, non-infectious diseases during the 1940's, there has emerged a periodic concern among epidemiologists regarding disciplinary boundaries and identity. With the development of hierarchical views of the natural history of human disease, the elaboration of mutation theories of chronic, non-infectious disease, and the identification of conceptual frameworks and causal relationships applicable to both the infectious and chronic, non-infectious diseases, it has become possible to reconsider the definitions and scope of epidemiology from within the confines of general epidemiologic-pathologic theory. Based upon natural history and discipline-related concepts of causation, it is possible to integrate the epidemiological and pathological characteristics of disease into a single, coherent systematic epidemiologic theory. Within these conceptual/axiomatic frameworks, systematic epidemiology emerges as the study of disease causality and control and is generally applicable to both the infectious and the chronic, non-infectious (i.e., neoplastic) diseases. Because epidemiologic theory begins with pathologic theory, it is fitting that systematic epidemiologic theory embrace both epidemiology and pathology as complimentary conceptual approaches to the comprehension of disease. Because the interdependent efforts of epidemiology and pathology provide the conceptual basis for action, it is also fitting that systematic epidemiologic theory embrace preventive medicine and public health as operational approaches to the control of disease.

Communicable Diseases↗

PubMed2005

Surgical technique--unwrapping the neck node levels around a sternocleidomastoid muscle bar: a systematic way of performing (modified) radical neck dissection.

AIM: Description of a systematic approach to the neck for removal of lymph node bearing tissues in levels I-V. METHOD: A (modified) radical neck dissection is divided in three steps: (1) Dissection of levels I-IV, (2) dissection of level V and (3) transection of SCM bar and finalisation of the dissection. The sternocleidomastoid muscle (SCM) is used as a "bar", around which the different neck levels can be systematically unwrapped, warranting permanent cranio-caudal tension of the neck specimen, while anatomical relations remain intact. RESULTS: In a group of 115 (modified) radical en bloc neck dissections with or without post-operative radiotherapy 10% regional recurrences, 2% post-operative chylous fistulas and < 5% post-operative wound infections occurred. The overall 5 years survival was 45% (95% confidence interval: 36-54%). CONCLUSION: A systematic unwrapping of lymph node levels around the sternocleidomastoid bar provides a reliable systematic method for performing (modified) radical neck dissections without a negative influence on clinical outcome.

Head and Neck Neoplasms↗

PubMed2006

A systematic and efficient method to estimate the vibrational frequencies of linear peptide and protein ions with any amino acid sequence for the calculation of Rice-Ramsperger-Kassel-Marcus rate constant.

A systematic method to automatically estimate the vibrational frequency sets of linear peptide and protein ions with any amino acid sequence, which is needed in Rice-Ramsperger-Kassel-Marcus (RRKM) calculations for dissociation of these ions, has been developed. The method starts from the frequencies of free amino acids calculated quantum chemically at the DFT/B3LYP/6-31G** level. Some of these were systematically eliminated to get fictitious sets of frequencies for each amino acid at the C-terminus, N-terminus, and inside the chain. By collecting these sets as needed for a specified amino acid sequence and adding vibrations appearing upon peptide bond formation and protonation, a complete set of vibrational frequencies was obtained. Other conditions for RRKM calculations have also been systematically specified. RRKM calculations performed under various conditions have shown that the present method can be useful for an order of magnitude estimation of a statistical rate constant even at low internal energy region. The fact that arbitrariness involved in constructing an entire frequency set simply through spectral correlation can be avoided, and that any protein ion can be handled systematically and rapidly once its sequence and the number of protons attached are specified, are the main advantages of the present method.

Algorithms↗