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Dose selection for prostate cancer patients based on dose comparison and dose response studies.

PURPOSE: To better define the appropriate dose for individual prostate cancer patients treated with three-dimensional conformal radiation therapy (3D CRT). METHODS AND MATERIALS: Six hundred eighteen patients treated with 3D CRT between 4/89 and 4/97 with a median follow-up of 53 months are the subject of this study. The bNED outcomes were assessed by the American Society for Therapeutic Radiology and Oncology (ASTRO) definition. The patients were grouped into three groups by prostate-specific antigen (PSA) level (<10 ng/ml, 10-19.9 ng/ml, and 20+ ng/ml) and further subgrouped into six subgroups by favorable (T1, 2A and Gleason score < or =6 and no perineural invasion) and unfavorable characteristics (one or more of T2B, T3, Gleason 7-10, perineural invasion). Dose comparisons for bNED studies were made for each of the six subgroups by dividing patients at 76 Gy for all subgroups except the favorable <10 ng/ml subgroup, which was divided at 72.5 Gy. Five-year bNED rates were compared for the median dose of each dose comparison subgroup. Dose response functions were plotted based on 5-year bNED rates for the six patient groupings, with the data from each of the six subgroups divided into three dose groups. The 5-year bNED rate was also estimated using the dose response function and compares 73 Gy with 78 Gy. RESULTS: Dose comparisons show a significant difference in 5-year bNED rates for three of the six subgroups but not for the favorable <10 ng/ml, the favorable 10-19.9 ng/ml, or the unfavorable > or =20 ng/ml subgroups. The significant differences ranged from 22% to 40% improvement in 5-year bNED with higher dose. Dose response functions show significant differences in 5-year bNED rates comparing 73 Gy and 78 Gy for four of the six subgroups. Again, no difference was observed for the favorable <10 ng/ml group or the unfavorable > or =20 ng/ml group. The significant differences observed in 5-year bNED ranged from 15% to 43%. CONCLUSIONS: Dose response varies by patient subgroup, and appropriate dose can be estimated for up to six subdivisions of prostate cancer patients. The appropriate use of high dose with 3D CRT results in 5-year cure rates that equal or exceed other treatments. The national practice must be upgraded to allow the safe administration of 75-80 Gy with 3D CRT.

Dose-Response Relationship, Radiation↗

Two-dimensional display and whole genome comparison of bacterial pathogen genomes of high G+C DNA content.

High-resolution comparison of bacterial genomes facilitates the identification of the genetic changes responsible for clinically relevant phenotypes. For this purpose we have established a method for the display and comparison of high G+C bacterial genomes in two dimensions. Here we describe the application of two-dimensional bacterial genomic display to resolve the genomes of Bordetella pertussis, Mycobacterium avium and Mycobacterium tuberculosis, and its utility in strain comparison and detection of insertion and substitution mutations.

Bacteria↗

[Multiple comparison procedures: principles, limits. Applications to microarray phenotype-genotype analysis].

BACKGROUND: When analysing data which simultaneously implicate a large number of statistical tests, one of the main problems is to take into account the multiplicity of these tests. The huge amount of comparisons done in studies of which the aim is to detect, using microarray, genes whose transcriptional changes are related to a biological or clinical outcome leads to a renewed interest for the multiple comparisons problem. However, this problem concerns many other fields such as psychometry, epidemiology, genetics. RESULTS: First, we introduce the multiple comparison framework. Then, we present the main procedures based on a global error rate called the "Family Wise Error Rate" (FWER) and those based on a false discovery rate expectancy (the "False Discovery Rate" (FDR) and the "positive False Discovery Rate" (pFDR)). Next, we apply the different procedures on a real dataset from a breast carcinoma study. Finally, we discuss the main results and we present guidelines for the use of these procedures.

False Positive Reactions↗

Comparison of high pulse repetition frequency and continuous wave Doppler echocardiography in the assessment of high flow velocity in patients with valvular stenosis and regurgitation.

Continuous wave Doppler echocardiography has proved useful in detecting and quantitating the high velocity flow disturbances that characterize many stenotic and regurgitant valvular lesions. Pulsed Doppler echocardiography, in contrast, is limited in its ability to quantitate the high velocities that are detected. Recently, new pulsed Doppler systems have been developed that employ high pulse repetition frequencies and can theoretically measure higher flow velocities than those measured by the standard pulsed Doppler systems. To determine the ability of high pulse repetition frequency Doppler echocardiography to accurately measure high velocity flow signals in comparison with the continuous wave method, 80 patients undergoing routine echocardiographic examination for the assessment of valvular heart disease were studied using both techniques. A total of 113 high velocity flow disturbances were detected in 68 patients. In 41 instances, the maximal velocities by the two methods were within 0.5 m/s of each other. In 68 of the 113 high velocity lesions, however, the high pulse repetition frequency technique underestimated the peak velocity found with continuous wave Doppler echocardiography by more than 0.5 m/s. Comparison of the peak velocities recorded by the two methods for the total group showed no significant correlation (r = 0.04, p = NS). Comparison of the difference in peak velocities obtained by the two techniques with the maximal continuous wave velocity (n = 94, r = 0.70, slope = 0.71) suggested that the underestimation becomes greater as the peak velocity increases. Fifteen of the study patients with aortic stenosis subsequently underwent catheterization.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

Suppression of sustained ventricular tachyarrhythmias: a comparison of d,l-sotalol with no antiarrhythmic drug treatment.

OBJECTIVES: This study evaluates the clinical efficacy of d,l-sotalol in patients with sustained ventricular tachyarrhythmias. BACKGROUND: D,l-sotalol is an important antiarrhythmic agent to prevent recurrences of sustained ventricular tachyarrhythmias (VT/VF). However, evidence is lacking that an antiarrhythmic agent like d,l-sotalol can reduce the incidence of sustained ventricular tachyarrhythmias in comparison to no antiarrhythmic drug treatment. METHODS: A prospective study was performed in 146 consecutive patients with inducible sustained ventricular tachycardia or ventricular fibrillation. In 53 patients, oral d,l-sotalol prevented induction of VT/VF during electrophysiological testing and patients were discharged on oral d,l-sotalol (sotalol group). In 93 patients, VT/VF remained inducible and a defibrillator (ICD) was implanted. After implantation of the device patients were randomly assigned to oral treatment with d,l-sotalol (ICD/sotalol group, n=46) or no antiarrhythmic medication (n=47, ICD-only group). RESULTS: During follow-up, 25 patients (53.2%) in the ICD-only group had a VT/VF recurrence in comparison to 15 patients (28.3%) in the sotalol group and 15 patients (32.6%) in the ICD/sotalol group (p=0.0013). Therapy with d,l-sotalol, amiodarone or metoprolol was instituted in 12 patients (25.5%) of the ICD-only group due to frequent VT/VF recurrences or symptomatic supraventricular tachyarrhythmias. In nine patients, 17% of the sotalol group, an ICD was implanted after VT/VF recurrence, three patients (5.7%) received amiodarone. Total mortality was not different between the three groups. CONCLUSIONS: D,l-sotalol significantly reduces the incidence of recurrences of sustained ventricular tachyarrhythmias in comparison to no antiarrhythmic drug treatment.

Administration, Oral↗

Optimal right ventricular pacing site in chronically implanted patients: a prospective randomized crossover comparison of apical and outflow tract pacing.

OBJECTIVES: To evaluate the long-term functional and hemodynamic effects of right ventricular outflow tract (RVOT) pacing by comparison with right ventricular apical (RVA) pacing. BACKGROUND: Acute studies have suggested that RVOT pacing could significantly improve cardiac performance in comparison with RVA pacing but no data are available in chronically implanted patients. METHODS: Sixteen patients with chronic atrial tachyarrhythmia and complete AV block were included. Left ventricular ejection fraction (LVEF) was > or =40% in ten and <40% in six. Patients were implanted with a standard DDDR pacemaker connected to two ventricular leads. A screw-in lead was placed at the RVOT and connected to the atrial port. A second lead was positioned at the RVA and connected to the ventricular port. Right ventricular outflow tract and RVA pacing was achieved by programming either the AAIR or the VVIR mode respectively. Four months later patients were randomized so as to undergo either RVOT or RVA pacing for three months according to a blind crossover protocol. Apart from the pacing mode, programming remained unchanged throughout the study. At the end of each period, NYHA class, LVEF, exercise time and maximal oxygen uptake were assessed. RESULTS: No significant difference was observed between the two modes for all the parameters analyzed. These identical results were observed in all patients globally, in patients with LVEF > or =40% as in those with LVEF <40%. CONCLUSIONS: Within the limits of this study, no symptomatic improvement or hemodynamic benefit was noted after three months of RVOT pacing, by comparison with RVA pacing.

Aged↗

A comparison of 12- and 15-lead ECGS in ED chest pain patients: impact on diagnosis, therapy, and disposition.

The objective of this study was to investigate the diagnostic and therapeutic impact of the 15-lead electrocardiogram (15ECG) on the emergency department (ED) management of chest pain (CP) patients. The design was prospective use of 15ECG with real-time physician survey and retrospective comparison to 12-lead ECG (12ECG). The study took place in a University hospital ED. Adult CP patients participated. During the 15ECG period (June 1996 to July 1996), 595 patients (92% of CP patients) had 15ECG analysis. Diagnoses of acute coronary ischemic syndromes (ACIS) were as follows: 13 acute myocardial infarction (AMI, 7 anterior [ANT], 5 inferior [INF], 1 lateral [LAT], 2 posterior [POST], 1 right ventricular [RV]) and 136 unstable angina (USA) with 47% exhibiting ECG abnormality; the 2 POST and 1 RV AMI occurred in the setting of coexisting INF AMI. The following management strategies were used: 6 fibrinolytic therapy (TT), 4 primary angioplasty (PTCA), 67 rule-out myocardial infarction (ROMI), and 144 admission to critical care unit (CCU). During the 12ECG period (June 1995 to July 1995), 599 patients were encountered. The diagnoses of ACIS were as follows: 11 AMI (5 ANT, 4 INF, 2 LAT) and 146 USA with 51% exhibiting ECG abnormality (P = NS for diagnostic comparisons to 15ECG). The following management strategies were used: 5 TT, 5 PTCA, 59 ROMI, and 137 admission to CCU (P = NS for all treatment comparisons to 15ECG). Of 15ECG cases 81% had completed real-time physician survey, showing that the diagnosis and management ACIS were not altered by the 15ECG; physicians felt, however, that the 15ECG provided a more complete anatomic picture of the ACIS. No false-positive cases of additional lead STE were noted in this investigation except in cases involving abnormal intraventricular conduction such as the bundle branch block scenario. The 15ECG provided a more complete description of myocardial injury without altering the ED diagnosis, ED-based therapy, or hospital disposition in adult CP patients. Further study is required to identify patient subset(s) which may benefit from the 15ECG.

Angina, Unstable↗

Comparison of load transmission and bracket deformation between titanium and stainless steel brackets.

This study measures the load transmitted and structural integrity of stainless steel and titanium brackets on application of torsional forces. Both 0.018 and 0.022 inch slot size edgewise brackets were tested in a specially designed apparatus that applied a torque value of 45 degrees. The load generated was measured by an Instron Universal Testing Machine at intervals of 15 degrees, 30 degrees, and 45 degrees of torque application. The structural stability of the brackets was evaluated by measuring the bracket slot width with a traveling stereoscopic microscope before and after the brackets were subjected to torsional forces. The specimen population was composed of 80 brackets and 80 wire specimens. An independent sample t test was used for comparison of mean load generated at 45 degrees of torque application. Repeated measures ANOVA (one-way) comparison was used to evaluate changes in load at different torque levels for the stainless steel and titanium brackets. A paired t test (two-tail) was used to determine the difference between initial and final bracket slot width at 45 degrees of torque applied for the two bracket types. The titanium brackets transmitted higher loads at 15 degrees and 30 degrees torque and lower load at 45 degrees torque on application of torsional forces in comparison to stainless steel brackets. The titanium brackets demonstrated superior dimensional stability compared to stainless steel brackets (P < .0001).

Analysis of Variance↗

Hospital-acquired infections in the United States. The importance of interhospital comparisons.

To use infection rates as a basis for measuring quality of care, the rates must be meaningful for interhospital comparison. A crude, overall nosocomial infection rate of a hospital provides no means of adjustment for patients' intrinsic or extrinsic risks. Before interhospital comparison, rates should be adjusted for nosocomial infection risk factors. Interhospital comparison of rates requires that a hospital participate in a multicenter surveillance system or aggregated national database. This article outlines a series of questions for hospital administrations to pose before entering such an endeavor.

Cross Infection↗

Comparison of different methods to estimate prevalence of drug use by using pharmacy records.

Several methods to estimate prevalence of drug use are available, which may complicate a valid comparison of these estimates. Standardization may contribute to more valid comparisons. We compared different methods to estimate prevalence of drug use by using pharmacy records. Data were obtained from the Dutch population-based PHARMO-database comprising medication histories of 300,000 subjects. Five point prevalences and a 1-year prevalence of cholesterol-lowering drug use were estimated in 1995. Four point prevalences differed in data handling before estimating prevalence (e.g., correction for irregular drug use or construction of episodes of drug use). The numerator of the fifth point prevalence estimate represented the number of defined daily doses (DDDs) instead of the number of patients filling a prescription. The first four point prevalences ranged from 11.0-12.1 per thousand. Prevalence ratio (male:female) was 1.2 for these methods. The fifth method resulted in an estimate similar to the other point prevalences (11.9 DDDs/1000 inhabitants). However, the prevalence ratio was 1.4 due to larger average number of DDDs prescribed to men. One year-prevalence was 4-5 per thousand higher than point prevalences. The comparison of these methods indicated that the choice of prevalence measure (point versus period prevalence) substantially influenced the prevalence estimate, whereas the influence of data handling was negligible. For standardization purposes in drug utilization research, we recommend estimating point prevalence instead of period prevalence. The various methods of data handling before estimating point prevalence yielded similar results and therefore we cannot recommend one specific method. However, defined daily doses should not be used to estimate (point) prevalences of drug use because this measure is significantly influenced by prescribed dosage regimens.

Adult↗

Abstruse comparisons: the problems of numerical contrasts of two groups.

The most common quantitative comparison in medical literature is a contrast of two numbers, such as two means or two rates. The two numbers, A and B, can be compared as a direct increment (A-B), ratio (A/B), relative change ([A-B]/B), or other index of contrast. To appreciate the quantitative distinction, a reader must know the "setting" reflected by the basic values of A and B. For example, a ratio of 2.0 does not distinguish comparisons between rates of 60% versus 30% and 0.006% versus 0.003%. Despite the frequency of published comparisons, they can be expressed with two types of abstrusity: quantitatives, if the basic values for A and B are not readily evident; and qualitative, if the component underlying variables are unfamiliar and not suitably explained. Among the published articles during the first six months of 1995 for JAMA and New England Journal of Medicine, 57 that satisfied inclusion criteria were reviewed for compliance with standards for avoiding the two types of abstrusity. The standards for quantitative abstrusity were applied to the published abstract-summary, because it is often the only "sound bite" that is read and remembered by most readers. The standards for qualitative abstrusity, however, could be fulfilled in the text, not just in the abstract-summaries of each article. Among the 57 abstract-summaries, 30% were abstruse quantitatively, and 11 (48%) of 23 pertinent papers were qualitatively abstruse. Abstrusity can be eliminated if authors and editors insist that quantitative contrasts cite the basic numbers being compared and the meaning of the associated variables and their rating scales.

Bias↗

Lateralized brain dysfunction in schizophrenia: a comparison with patients with lateralized structural lesions.

A comparison was made among participants with schizophrenia and those with structural lateralized or diffuse brain damage in order to determine the extent to which the cognitive profile of the schizophrenia sample resembled the profiles obtained from patients with left-hemisphere, right-hemisphere, and diffuse brain damage. The Halstead-Reitan Neuropsychological Battery was used as the testing procedure. The data were subjected to discriminant analysis in order to obtain frequencies of predicted classification of the participants with schizophrenia into schizophrenia, left-hemisphere, right-hemisphere, and diffuse groups. Half of the participants with schizophrenia were classified into the schizophrenia group. The other half was evenly distributed across the left-hemisphere, right-hemisphere, and diffuse brain damage groups. There was not a disproportionately large number of participants classified into the left-hemisphere group. Comparisons among these four predicted groups were accomplished for each of the Halstead-Reitan Battery measures using one-way analysis of variance. The comparison of the subtest scores among the predicted groups indicated that the patients classified into the left-hemisphere group were characterized by a pattern of language dysfunction thought to be developmental in nature, and an abnormal lack of asymmetry in tapping speed favoring the right hand.

Adult↗

Event-related brain potentials dissociate visual working memory processes under categorial and identical comparison conditions.

Event-related potentials (ERPs) have been successfully employed to examine the functional and neuronal characteristics of working memory processes. In the present study, we examined the ERP waveforms in a delayed matching task to examine the cognitive processes underlying category and identity comparison and the effects of stimulus complexity. Subjects had to decide whether two visual stimuli are (a) physically identical (identical comparison condition, IC) or (b) identical, irrespective of their orientation (categorial comparison condition, CC). The stimuli were structured five-point patterns, which varied in complexity. For the ERPs elicited during the 1500 ms retention interval, the following pattern of results was obtained: Stimuli in the CC-condition elicited larger P300 components than in the IC-condition. In the IC-condition, the P300 was followed by a broadly distributed negative slow wave. Moreover, complex patterns elicited a posteriorily distributed negativity at 350 ms (N350), whereas the less complex patterns gave rise to a fronto-centrally distributed slow wave that started around 500 ms. These results suggest that S1 was more elaborately processed in the CC-condition, while the more complex figures were associated with an early classification process during the retention interval.

Adult↗

Structure of cDNAs encoding the triple-helical domain of murine alpha 2 (VI) collagen chain and comparison to human and chick homologues. Use of polymerase chain reaction and partially degenerate oligonucleotide for generation of novel cDNA clones.

Type VI collagen cDNAs of human and avian origin were recently obtained and characterized by screening cDNA libraries in lambda phage. Based on the published sequences of these cDNAs, we constructed partially degenerate oligonucleotide primers that we used in polymerase chain reactions for the generation of alpha 2(VI) collagen clones of murine origin. As template, we used cDNA derived from murine total RNA. We amplified, cloned and sequenced a 1043-bp fragment that contains the coding sequence for the entire triple-helical domain except for the first two amino acids that are Gly-Pro in both man and chicken. Comparison of the nucleotide and derived amino acid sequences revealed 84.6% and 92.5% identity between mouse and man at the DNA and protein levels, respectively. Comparison with chicken sequences showed 72% and 79.1% identity. The third base usage showed a distinct preference for A in the glycine codons for the three species; whereas, U is preferred in all human fibrillar collagen genes previously defined. The preference for third base codon in Y position prolines is U for the alpha 2(VI) collagen as it is for the human fibrillar collagen genes. A single cysteine at position 89, two Arg-Gly-Asp sequences, and one triple helix-interruption are conserved in mouse, man and chicken. Comparison of hydropathy plots showed great similarity between those of murine and human alpha 2(VI) collagen chains and to a lesser extent between murine and chick. Northern blot hybridization of murine poly A+ RNA with a nick-translated radiolabeled alpha 2(VI) collagen probe detected one major transcript of 3.7 kb.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗

Origin of multicellular eukaryotes - insights from proteome comparisons.

The complete genomes of the yeast Saccharomyces cerevisiae and the nematode worm Caenorhabditis elegans have recently become available allowing the comparison of the complete protein sets of a unicellular and multicellular eukaryote for the first time. These comparisons reveal some striking trends in terms of expansions or extensive shuffling of specific domains that are involved in regulatory functions and signaling. Similar comparisons with the available sequence data from the plant Arabidopsis thaliana produce consistent results. These observations have provided useful insights regarding the origin of multicellular organisms.

Animals↗

Surprising similarities in structure comparison.

Examination of a protein's structural 'neighbors' can reveal distant evolutionary relationships that are otherwise undetectable, and perhaps suggest unsuspected functional properties. In the past, such analyses have often required specialized software and computer skills, but new structural comparison methods, developed in the past two years, increasingly offer this opportunity to structural and molecular biologists in general. These methods are based on similarity-search algorithms that are fast enough to have effectively removed the computer-time limitation for structure-structure search and alignment, and have made it possible for several groups to conduct systematic comparisons of all publicly available structures, and offer this information via the World Wide Web. Furthermore, and perhaps surprisingly given the difficulty of the structure-comparison problem, these groups seem to have converged on quite similar approaches with respect to both fast search algorithms and the identification of statistically significant similarities.

Computer Communication Networks↗

Metabolism and evolution of Haemophilus influenzae deduced from a whole-genome comparison with Escherichia coli.

BACKGROUND: The 1.83 Megabase (Mb) sequence of the Haemophilus influenzae chromosome, the first completed genome sequence of a cellular life form, has been recently reported. Approximately 75 % of the 4.7 Mb genome sequence of Escherichia coli is also available. The life styles of the two bacteria are very different - H. influenzae is an obligate parasite that lives in human upper respiratory mucosa and can be cultivated only on rich media, whereas E. coli is a saprophyte that can grow on minimal media. A detailed comparison of the protein products encoded by these two genomes is expected to provide valuable insights into bacterial cell physiology and genome evolution. RESULTS: We describe the results of computer analysis of the amino-acid sequences of 1703 putative proteins encoded by the complete genome of H. influenzae. We detected sequence similarity to proteins in current databases for 92 % of the H. influenzae protein sequences, and at least a general functional prediction was possible for 83 %. A comparison of the H. influenzae protein sequences with those of 3010 proteins encoded by the sequenced 75 % of the E. coli genome revealed 1128 pairs of apparent orthologs, with an average of 59 % identity. In contrast to the high similarity between orthologs, the genome organization and the functional repertoire of genes in the two bacteria were remarkably different. The smaller genome size of H. influenzae is explained, to a large extent, by a reduction in the number of paralogous genes. There was no long range colinearity between the E. coli and H. influenzae gene orders, but over 70 % of the orthologous genes were found in short conserved strings, only about half of which were operons in E. coli. Superposition of the H. influenzae enzyme repertoire upon the known E. coli metabolic pathways allowed us to reconstruct similar and alternative pathways in H. influenzae and provides an explanation for the known nutritional requirements. CONCLUSIONS: By comparing proteins encoded by the two bacterial genomes, we have shown that extensive gene shuffling and variation in the extent of gene paralogy are major trends in bacterial evolution; this comparison has also allowed us to deduce crucial aspects of the largely uncharacterized metabolism of H. influenzae.

Bacterial Proteins↗

Video-assisted thoracoscopic surgery versus thoracotomy for recurrent spontaneous pneumothorax. A comparison of results and costs.

OBJECTIVE: Video-assisted thoracoscopic surgery (VATS) represents at present the most suitable treatment of recurrent spontaneous pneumothorax. After three years we consider this interesting to draw up a trial balance of our VATS experience in comparison with the cases treated before 1991 with the classic thoracotomic approach. METHODS: We have considered retrospectively the results obtained in a series of 30 consecutive patients with recurrent spontaneous pneumothorax treated with VATS between November 1991 and August 1994 in comparison with those obtained in a group of 30 patients previously treated with a traditional thoracotomy. The groups have been selected in such a way that surgical indications, sex ratio, age and number of episodes were homogeneous. The parameters we have compared were the postoperative complications, the duration of chest drainage and hospitalization, the operating times and the relapses. Besides these technical parameters we considered the economic data too. RESULTS: On average drains removal occurred one day before in VATS-Group: the time spent in the Hospital was significantly shorter in VATS-Group, being on average 1 week. Short term complications may be considered similar in the two Groups. Prolonged air leaks occurred in 13% and 16% respectively. Emothorax requesting reoperation occurred in 1 case for each Group. One death occurred in thoracotomy-Group in an old patient presenting a severe chronic respiratory insufficience with exacerbation in postoperative time. We have registered 2 relapses after VATS and none after thoracotomy. CONCLUSIONS: The study has demonstrated the therapeutic efficacy of VATS and in the same time that in VATS the total economic cost is lower (22.7%) in comparison with traditional thoracotomy.

Adolescent↗