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PubMed1994

The performance of the O'Brien-Fleming multiple testing procedure in the presence of intraclass correlation.

Assuming that all subject responses were independent, O'Brien and Fleming (1979, Biometrics 35, 549-556) proposed a simple and useful multiple testing procedure for clinical trials for comparing two treatments with dichotomous data. Differences in the methods of evaluating subject responses at each evaluation time, however, may induce an intraclass correlation among these responses used in calculating the O'Brien-Fleming multiple testing procedure. On the basis of Monte Carlo simulations, we note that even a small intraclass correlation among subject responses in the same analysis can substantially inflate the Type I error of the O'Brien-Fleming multiple testing procedure. Furthermore, this inflation generally increases as either the number of analyses or the underlying response probability increases. We also have demonstrated that if we were able to maintain a uniform medical test procedure between the two treatments for each analysis, the actual Type I error of the O'Brien-Fleming multiple testing procedure may conversely become conservative.

Analysis of Variance↗
PubMed2000

Predictors of conversion to sinus rhythm using ibutilide for atrial fibrillation or flutter.

To determine what factors can predict conversion to sinus rhythm, we retrospectively studied 201 consecutive patients who received ibutilide for treatment of atrial fibrillation or flutter. On multivariate analysis, the following factors were significantly associated with conversion: recent onset of arrhythmia, an underlying atrial flutter rhythm, lack of a history of congestive heart failure, and lack of concomitant digoxin therapy.

Aged↗
PubMed1977

Single and multiple ion recording techniques for the analysis of diphenylhydantoin and its major metabolite in plasma.

A method has been developed for single ion monitoring of diphenylhydantoin and its major metabolite 5-(p-hydroxyphenyl)-5-phenylhydantoin in plasma. A plasma extract is reacted with N,O-bis(trimethylsilyl) acetamide and single ion recording is carried out using a gas chromatograph mass spectrometer system. The mass value selected, m/e 254, is common to the TMS ethers of diphenylhydantoin and its principal metabolite 5-(p-hydroxyphenyl)-5-phenylhydantoin. The result indicate that one cause of an adverse reaction to diphenylhydantoin could be a reduced ability to hydroxylate the drugmquantitative methods for the analysis of the drug and its major metabolite have also been developed. Diphenylhydantoin and 5-(p-hydroxyphenyl)-5-phenylhydantoin can be analysed in plasma after addition of deuterium labelled internal standards and conversion to volatile derivatives for mass fragmentographic analysis. Diphenylhydantoin and its internal standard are analysed as the N,N-dimethyl derivative, and the hydroxylated metabolite and its internal standard are converted to a petrimethylsilyl compound by reaction with N,O-bis-(trimethylsilyl)acetamide.

Chromatography, Gas↗
PubMed2004

The US EPA reference dose for methylmercury: sources of uncertainty.

The US Environmental Protection Agency (EPA) derived a reference dose for methylmercury in 2001, based on an extensive analysis by the National Research Council (NRC) of the National Academy of Sciences. The NRC performed benchmark dose analysis on a number of endpoints from three longitudinal prospective studies: the Seychelles Islands, the Faroe Islands, and the New Zealand studies. Adverse effects were reported in the latter two studies, but not in the Seychelles study. The NRC also performed an integrative analysis of all three studies. Dose conversion from cord blood or maternal hair mercury concentration was performed by EPA using a one-compartment pharmacokinetic model. A total uncertainty factor of 10 was applied for intrahuman pharmacokinetic and pharmacodynamic variability. There are numerous decisions made by the NRC/EPA that could greatly affect the value of the reference dose (RfD). Some of these include the choice of a linear model for the relationship between mercury body burden and neuropsychological performance, the choice of values of P0 and the benchmark response, the use of the "critical study/critical endpoint" approach in the interpretation of the maternal body burden that corresponds to the RfD, the use of central tendencies in a one-compartment pharmacokinetic model rather than the inclusion of the distributions of variables for the population of reproductive-age women, the assumption of unity for the ratio of fetal cord blood to maternal blood methylmercury concentrations, the choice of a total of 10 as an uncertainty factor, and the lack of dose-response analysis for other health effects such as cardiovascular disease. In addition, it may be argued that derivation of a RfD for methylmercury is inappropriate, given that there does not appear to be a threshold for adverse neuropsychological effects based on available data.

Adult↗
PubMed2005

Optimization of lipase-catalyzed synthesis of octyl hydroxyphenylpropionate by response surface methodology.

The ability of immobilized lipase Candida antarctica (Novozyme 435) to catalyze the direct esterification of hydroxyphenylpropionic acid and octanol in a solvent-free system was investigated in this study. Response surface methodology (RSM) and five-level-four-factor central composite rotatable design (CCRD) were employed to evaluate the effects of synthesis parameters, such as reaction time, temperature, enzyme amount, and pH memory, on percentage molar conversion of phenolic acid esters. Reaction time, temperature, and enzyme amount were the most important variables. On the basis of canonical analysis and ridge max analysis, the optimum synthesis conditions with 95.9% molar conversion were reaction time of 58.2 h, temperature of 52.9 degrees C, enzyme amount of 37.8% (w/w), and pH memory of pH 7.

Antioxidants↗
PubMed2006

Predicting conversion to open surgery in laparoscopic left hemicolectomy.

PURPOSE: The objective of this study was to quantify the risk of conversion to open surgery of laparoscopic left hemicolectomy at an early stage of the learning curve. METHODS: A multiple logistic regression analysis of 100 laparoscopic left hemicolectomies completed between April 2001 and May 2004 was performed. RESULTS: The overall conversion rate was 12%. At univariate analysis, 2 factors were found to be predictive of conversion to open surgery: malignancy (17.2% vs. 5%; P=0.046), and weight level (<60 kg=6.1%; 60 to 90 kg=11.3%; >90 kg=28.6%; P=0.049). At multiple logistic regression, the risk of conversion rose only for patients weighing more than 90 kg. CONCLUSIONS: On the basis of the results of this study, the surgeon will be able to quantify the risk of conversion to laparotomy with some precision in order to obtain the informed consent of the first 100 patients to whom laparoscopic left hemicolectomy is proposed.

Colectomy↗
PubMed2004

The meiotic recombination hot spot ura4A in Schizosaccharomyces pombe.

The meiotic recombination hot spot ura4A (formerly ura4-aim) of Schizosaccharomyces pombe was observed at the insertion of the ura4+ gene 15 kb centromere-proximal to ade6 on chromosome III. Crosses heterozygous for the insertion showed frequent conversion at the heterology with preferential loss of the insertion. This report concerns the characterization of 12 spontaneous ura4A mutants. A gradient of conversion ranging from 18% at the 5' end to 6% at the 3' end was detected. A novel phenomenon also was discovered: a mating-type-related bias of conversion. The allele entering with the h+ parent acts preferentially as the acceptor for conversion (ratio of 3:2). Tetrad analysis of two-factor crosses showed that heteroduplex DNA is predominantly asymmetrical, enters from the 5' end, and more often than not covers the entire gene. Restoration repair of markers at the 5' end was inferred. Random spore analyses of two-factor crosses and normalization of prototroph-recombinant frequencies to physical distance led to the demonstration of map expansion: Crosses involving distant markers yielded recombinant frequencies higher than the sum of the frequencies measured in the subintervals. Finally, marker effects on recombination were defined for two of the ura4A mutations.

Alleles↗
PubMed1989

Frequency analysis of accommodation: single sinusoids.

We present an experimental frequency analysis of a neurological control system, the accommodation system, using single sinusoids. Also, by means of continual experimental calibration full coverage of one subject's dynamic range, we demonstrate an AC nonlinearity saturation, which probably lies in the motor-response portion of the system; in contrast to the switching-mode nonlinearity, which probably lies in the sensory-processing portion. We offer our findings as a basis for further models. In addition, our results can be compared with studies using multiple sinusoids and transients to document how the different aspects of the accommodation system are realized given their different input conditions.

Accommodation, Ocular↗
PubMed1991

Expression of the cystic fibrosis transmembrane conductance regulator gene in cells of non-epithelial origin.

Consistent with the fact that the clinical disorder cystic fibrosis (CF) is manifested on epithelial surfaces, active transcription of the CF transmembrane conductance regulator (CFTR) gene and CFTR mRNA transcripts are detectable in a variety of epithelial cells, suggesting CFTR gene expression might be epithelial cell-specific. However, analysis of the CFTR gene promoter suggests it is a housekeeping gene, implying more widespread expression than only in epithelial cells. To evaluate the latter hypothesis, various human cells of non-epithelial origin, including lung fibroblasts, U-937 histiocytic lymphoma cells, K-562 erythroleukemia cells, HL-60 promyelocytic leukemia cells as well as freshly isolated blood lymphocytes, neutrophils, monocytes, and alveolar macrophages were examined for CFTR gene expression. Although Northern analysis failed to show CFTR mRNA transcripts in these cells, amplification of mRNA (after conversion to cDNA) by polymerase chain reaction combined with Southern analysis demonstrated the presence of CFTR mRNA transcripts at low levels in all cells evaluated except HL-60 cells. Comparative quantitative analysis showed fibroblasts contained 200-400 fold less CFTR mRNA transcripts than the T84 and HT-29 colon carcinoma epithelial cell lines, but had similar levels of CFTR transcripts to those of other epithelial cell lines. Nuclear transcription run-on analyses demonstrated very low level CFTR gene transcription in fibroblasts and U-937 cells, similar to that of other epithelial cells, but lower than the T84 and HT-29 colon carcinoma cell lines. Interestingly, while chromatin DNA of fibroblasts had no DNase I hypersensitivity sites in the 5' flanking region of the CFTR gene, HT-29 chromatin DNA exhibited four DNase I accessible sites in the same region, suggesting that these sites may be related to more active transcription of the CFTR gene in the intestinal epithelial cells than in fibroblasts.

Base Sequence↗
PubMed1994

Analysis of individual immunoglobulin lambda light chain genes amplified from single cells is inconsistent with variable region gene conversion in germinal-center B cell somatic mutation.

Responding B cells in specific immune responses diversify their immunoglobulin genes and are selected on their variant antigen receptors in the microenvironment of the germinal center. The patterns of mutations previously reported for immunglobulin (Ig) genes have supported mechanistic hypotheses of either error-prone DNA synthesis or templated variable region gene conversion as the underlying mechanism in the generation of these mutations. To assess the role of gene conversion in germinal-center somatic mutation, we chose to examine nucleotide changes in mouse lambda light chain genes which arose in response to a specific antigen. Laboratory mice possess three V lambda subexons, two of which differ from one another by only seven nucleotides, making these two subexons ideal for gene conversion. In the current study, we used six-parameter flow cytometry to isolate single lambda light chain-expressing germinal-center B cells from two different time points in a primary immune response. We then individually amplified and sequenced individual V lambda 1 genes from these single cells for mutational analysis. None of the 32 V lambda 1 genes, containing a total of 40 mutations, showed evidence of gene conversion from either of the other V lambda subexons. Features such as the replacement to silent ratio of the mutations documented at the earlier time point indicate an absence of antigen-driven selection. These data indicate that V region gene conversion does not contribute to germinal-center somatic mutation and that gene conversion is not responsible for targeting mutation specifically to rearranged Ig genes. The biological implications are discussed.

Amino Acid Sequence↗
PubMed1990

The effects of porcine somatotropin and dietary lysine on growth performance and carcass characteristics of finishing swine.

Seventy-two finishing pigs (initial weight = 57.6 kg) were utilized to determine the effects of porcine somatotropin (pST) and dietary lysine level on growth performance and carcass characteristics. Pigs were injected daily with 4 mg pST in the extensor muscle of the neck and fed either a pelleted corn-sesame meal diet (.6% lysine, 17.8% CP) or diets containing .8, 1.0, 1.2 or 1.4% lysine provided by additions of L-lysine.HCl. All diets were formulated to contain at least twice the required amounts of other amino acids. Control pigs received a placebo injection and the .6%-lysine diet. Increasing levels of dietary lysine resulted in increased ADG and improved feed conversion (quadratic, P less than .01) for pST-treated pigs. The calculated daily lysine intake was 16.6, 13.6, 19.6, 25.1, 29.6 and 33.6 g for the control and pST-treated pigs fed .6, .8, 1.0, 1.2 and 1.4% lysine, respectively, over the entire experiment. Breakpoint analysis indicated that cumulative ADG and feed conversion were optimized at 1.19 and 1.22% lysine, respectively. Longissimus muscle area and trimmed ham and loin weights increased as dietary lysine was increased among pST-treated pigs (quadratic, P less than .01). Breakpoint analysis indicated that 1.11% lysine maximized longissimus muscle area, whereas trimmed ham and loin weights were maximized at .91 and .98% lysine, respectively. Adjusted backfat thickness was not affected by dietary lysine, but pST-treated pigs had less backfat (P less than .05) than control pigs did. Percentage moisture of the longissimus muscle increased (linear, P less than .05), as did percentage CP (quadratic, P less than .05), whereas fat content decreased (linear, P less than .05) as lysine level increased. Similar trends in composition were observed for muscles of the ham (semimembranosus, semitendinosus, and biceps femoris). Shear-force values from the longissimus and semimembranosus were lowest for control pigs, but they increased as dietary lysine level increased among pST-treated pigs. Sensory panel evaluations indicated that juiciness and tenderness decreased (linear, P less than .05) as dietary lysine level increased. Plasma urea concentrations decreased linearly (P less than .01) on d 28 as lysine level increased, whereas plasma lysine and insulin were increased (quadratic, P less than .01). Plasma glucose and free fatty acid concentrations on d 28 tended to increase (quadratic, P less than .10) with increasing dietary lysine level.(ABSTRACT TRUNCATED AT 400 WORDS)

Adipose Tissue↗
PubMed1998

Toxicity and efficacy of defined doses of CD4(+) donor lymphocytes for treatment of relapse after allogeneic bone marrow transplant.

Donor lymphocyte infusions (DLI) can induce remissions in patients who have relapsed after allogeneic bone marrow transplantation (BMT). However, DLI frequently also result in significant acute and/or chronic graft-versus-host disease (GVHD). Several clinical and experimental lines of evidence have suggested that CD8(+) T cells play a critical role in the pathogenesis of GVHD. To develop methods to reduce the incidence of GVHD associated with DLI, we administered defined numbers of CD4(+) donor T cells after ex vivo depletion of CD8(+) lymphocytes to 40 patients with relapsed hematologic malignancies after allogeneic BMT. Cohorts of patients received 0.3, 1.0, or 1.5 x 10(8) CD4(+) cells/kg. Overall, 12 of 38 patients (32%) evaluable for toxicity developed acute or chronic GVHD. However, 6 of 27 patients (22%) receiving 0.3 x 10(8) CD4 cells/kg developed GVHD compared with 6 of 11 patients (55%) who received >/=1.0 x 10(8) CD4 cells/kg (P = .07). Treatment-related mortality was low (3%), with 1 death related to infection in the setting of immunosuppression for GVHD. Disease responses after CD4(+) DLI were documented in 15 of 19 patients (79%) with early-phase chronic myelogenous leukemia (CML) relapse, 5 of 6 patients (83%) with relapsed multiple myeloma, and 1 patient with myelodysplasia. For patients with early-phase CML relapse, the Kaplan-Meier probability of achieving complete cytogenetic remission was 87% and the probability of complete molecular response was 78% at 1 year after DLI. The median time to complete cytogenetic response and molecular response in patients with CML was 13 weeks (range, 9 to 30 weeks) and 34 weeks (range, 10 to 56 weeks), respectively. The median time to response in patients with multiple myeloma was 26 weeks (range, 15 to 62 weeks). All patients in this trial who developed GVHD demonstrated tumor regression, but the presence of GVHD was not required for patients to achieve a response, because 48% of responding patients never developed evidence of GVHD. Two patients with CML who did not respond at dose level 1 subsequently achieved complete cytogenetic remission after a second infusion of CD8-depleted cells at dose level 2. In patients with evidence of mixed hematopoietic chimerism who achieved a complete remission after DLI, cytogenetic analysis of marrow cells also demonstrated conversion to complete donor hematopoiesis in all evaluable patients. These studies suggest that relatively low numbers of CD8-depleted donor lymphocytes are effective in inducing complete remissions in patients with stable-phase CML and multiple myeloma who have relapsed after allogeneic BMT. Because of the relatively low risk of toxicity associated with the infusion of defined numbers of CD4(+) donor cells, further studies can be undertaken in the setting of persistent minimal residual disease to prevent relapse after allogeneic BMT.

Adult↗
PubMed1991

Characterization of the spontaneous mutant H-2Kbm29 indicates that gene conversion in H-2 occurs at a higher frequency than detected by skin grafting.

A spontaneous mutation of H-2Kb, Kbm29, was discovered among the progeny of F1 hybrid parents. Unlike other characterized spontaneous class I variants, this mutant was detected with the use of antibody, rather than tissue grafting. Although Kbm29 is serologically indistinguishable from the previously described mutant molecule Kbm3, it is identical to the parental Kb by skin grafting and CTL assays. A full length cDNA of Kbm29 was amplified by polymerase chain reaction with locus-specific primers, cloned, and sequenced. Two nucleotides were found to be mutated, resulting in a single amino acid change (Lys----Ala) at amino acid 89 of the mature glycoprotein. This is consistent with the observed serologic changes, as the same amino acid substitution is responsible for the serologic profile of Kbm3. The occurrence of a mutation which is not detectable by the methods normally used to screen for H-2 mutants provides evidence that the high spontaneous rate of structural mutation described for the Kb molecule is underestimated.

Amino Acid Sequence↗
PubMed1993

Cognitive processes in social phobia.

Social phobics, anxious controls and non-patient controls took part in a brief videotaped conversation with a stooge in order to investigate the cognitive model of social phobia. Thoughts, behaviour, and attention during the conversation were assessed. Compared to the control groups, social phobics had more negative self-evaluative thoughts, performed less well, and systematically underestimated their performance. There were no differences in attention between the three groups. Content analysis of thought sampling data from the conversation, and from three hypothetical situations, revealed that few of the negative thoughts reported by social phobics explicitly mentioned evaluation by other people. This suggests that social phobics may not closely monitor other people's responses in social situations and hence that their thoughts are not data driven. The results are discussed in relation to the cognitive model of social phobia and suggestions are made for improvements in the treatment of social phobia.

Attention↗
PubMed1986

Comparison of immunochemical and radioligand binding assays for estrogen receptors in human breast tumors.

We have compared a new enzyme immunoassay (EIA) for estrogen receptors (ER) with our conventional radioligand binding assays (multipoint dextran-coated charcoal assay for cytoplasmic ER and hydroxylapatite exchange assay for nuclear ER). Cytoplasmic ERs were measured in 76 human breast cancer specimens by EIA and by five-point Scatchard analysis. The correlation between the two assays yielded a straight line with a slope of 0.92 (r = 0.95; P less than 0.001); conversely, in 31 nuclear salt extracts, linear regression analysis of hydroxylapatite exchange assay data with EIA showed a clear correlation (r = 0.93; P less than 0.001) but a slope of 1.7, demonstrating that EIA detects more ER sites. The binding of the antibody to the cytoplasmic ER molecules was investigated by sucrose density gradient analysis, which showed that EIA recognizes both cytoplasmic forms (9 and 3S), but does not distinguish between them. Advantages and drawbacks of this method are discussed with respect to its application for routine receptor determination for clinical management of breast cancer patients.

Breast Neoplasms↗
PubMed1999

Epidural anesthesia reduces length of hospitalization after endoluminal abdominal aortic aneurysm repair.

PURPOSE: The low invasiveness of endoluminal abdominal aneurysm repair (EAAR) appears optimal for the use of epidural anesthesia (EA). However, reported series on EAAR show that general anesthesia (GA) is generally preferred. To evaluate the feasibility and problems encountered with EA for EAAR, patients undergoing EAAR with EA and patients undergoing EAAR with GA were examined. METHODS: From April 1997 through October 1998, EAAR was performed on 119 patients at the Unit of Vascular Surgery at Policlinico Monteluce in Perugia, Italy. Four patients (3%) required conversion to open repair and were excluded from the analysis because they were not suitable candidates for evaluating the feasibility of EA. The study cohort thus comprised 115 patients undergoing abdominal aortic aneurysm (AAA) repair with the AneuRx Medtronic stent graft. The incidence of risk factors and anatomical features of the aneurysm were compared in patients selected for EA or GA on the basis of intention-to-treat analysis. Intraoperative and perioperative data were compared and analyzed on the basis of intention-to-treat and on-treatment analysis. RESULTS: Sixty-one patients (54%) underwent the surgical procedure with EA (group A), and 54 (46%) underwent the surgical procedure with GA (group B). Conversion from EA to GA was required in four patients (3 of 61 patients, 5%). There were no statistically significant differences between the two study groups in demographics, clinical characteristics, and American Society of Anesthesiology classification (ASA). There was no perioperative mortality. Major morbidity occurred in 3% of patients (group B). According to intention-to-treat analysis, no significant differences were observed between the two groups in mean operating time, fluoro time, blood loss, amount of contrast media used, mean units of transfused blood, need of intensive care unit, mean postoperative hospital stay, and postoperative endoleak. Conversely, significant differences were found by means of on-treatment analysis in the need of intensive care unit (0 vs 5 patients; P =.02), and length of hospitalization (2.5 vs 3.2 days; P =.04). Multivariate logistic regression analysis showed that GA and ASA 4 were positive independent predictors of prolonged (more than 2 days) postoperative hospitalization (hazard ratio, 2.5; 95% CI, 1.1 to 5.8; P =.03, and hazard ratio, 5.1; 95% CI, 1.5 to 17.9; P =.007, respectively). CONCLUSION: EA for EAAR is feasible in a high percentage of patients in whom it is attempted, and it ensures a technical outcome comparable with that of patients undergoing EAAR with GA. Successful completion of EAAR with EA is associated with a short period of hospitalization.

Aged↗
PubMed2001

Conversion therapy revisited: parameters and rationale for ethical care.

Observes that efforts are being made within certain professional counseling associations to oppose and prohibit attempts to modify homoerotic feelings and behavior on ethical grounds. Outlines several factors that can motivate the pursuit of conversion therapy and reviews data that suggest change is a viable treatment outcome. Proposes, based on an analysis of research data, an ethical framework within which conversion therapy can be legitimately practiced.

Behavior Therapy↗
PubMed1989

Conversion of deletions during recombination in pneumococcal transformation.

Genetic analysis of 16 deletions obtained in the amiA locus of pneumococcus is described. When present on donor DNA, all deletions increased drastically the frequency of wild-type recombinants in two-point crosses. This effect was maximal for deletions longer than 200 bases. It was reduced for heterologies shorter than 76 bases and did not exist for very short deletions. In three-point crosses in which the deletion was localized between two point mutations, we demonstrated that this excess of wild-type recombinants was the result of a genetic conversion. This conversion extended over several scores of bases outside the deletion. Conversion takes place during the heteroduplex stage of recombination. Therefore, in pneumococcal transformation, long heterologies participated in this heteroduplex configuration. As this conversion did not require an active DNA polymerase A gene it is proposed that the mechanism of conversion is not a DNA repair synthesis but involves breakage and ligation between DNA molecules. Conversion of deletions did not require the Hex system of correction of mismatched bases. It differs also from localized conversion. It appears that it is a process that evolved to correct errors of replication which lead to long heterologies and which are not eliminated by other systems.

Chromosome Deletion↗