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At least 667 records · Page 37Linked to original sources

PubMed1986

Pediatric emergency intravenous access. Evaluation of a protocol.

Effectiveness of a protocol for intravenous (IV) access during pediatric resuscitation was prospectively evaluated to determine whether utilization of a specified sequence of measures would reduce IV access time compared with resuscitations deviating from the protocol. The protocol involved rapid sequential attempts at percutaneous femoral vein catheterization, saphenous vein cutdown, and intraosseous infusions if initial percutaneous peripheral IV insertion failed. While no single technique provided completely reliable and rapid IV access, utilization of all techniques per protocol significantly improved IV access time. When initial percutaneous peripheral IV attempts failed, resuscitations in compliance with the protocol achieved IV access more rapidly (median, 4.5 minutes) than those deviating from the protocol (median, 10.0 minutes). Even with incomplete compliance, 66% of resuscitations achieved IV access within the first five minutes. Our experience indicates that IV access during pediatric resuscitation should rarely be delayed beyond the fifth minute if all available IV techniques are used.

Adolescent↗

PubMed1997

De novo malignancies after liver transplantation using tacrolimus-based protocols or cyclosporine-based quadruple immunosuppression with an interleukin-2 receptor antibody or antithymocyte globulin.

BACKGROUND: Although conventional immunosuppression after liver transplantation consists of cyclosporine A (CsA), steroids, and azathioprine, recently introduced protocols entail CsA-based quadruple induction protocols or tacrolimus-based combinations. These protocols aim to reduce the rejection rate and the considerable morbidity related to the side effects of additional immunosuppressive treatment, but have not yet been analyzed regarding their long term de novo neoplastic risk. METHODS: From September 1988 to May 1994, 500 liver transplantations were performed in 458 patients. The median follow-up was 50 months (range, 0.3-97 months) for all patients. Conventional triple therapy was implemented in 25 patients, CsA-based quadruple induction therapy using an antilymphocyte globulin preparation (ATG) in 190 patients, an interleukin-2 receptor antibody (BT563) in 141 patients, and tacrolimus-based dual or triple immunosuppression in 102 patients. The different protocols were evaluated in four randomized and two nonrandomized prospective trials. RESULTS: De novo neoplasias were detected in 33 patients (7.2%) and were comprised of lymphomas (n = 7), skin malignancies (n = 8 lesions in 7 patients), intraepithelial neoplasias of the cervix uteri (n = 7), breast carcinoma (n = 3), lung carcinoma (n = 3), and other malignancies (n = 6). The incidence of de novo neoplasias did not differ in the different trial arms. Only a positive T-crossmatch and a low CD4+/CD8+ ratio in patients receiving CsA-based immunosuppression demonstrated a significant correlation with the development of a de novo tumor in a multivariant logistic regression analysis. CONCLUSIONS: The development of de novo neoplastic diseases after liver transplantation with the use of CsA-based quadruple induction protocols or tacrolimus-based regimens for immunosuppresion was assessed over the long term. Recently introduced immunosuppressive protocols did not alter the posttransplant de novo tumor rate. Patients with a low CD4+/CD8+ ratio during CsA-based therapy or a positive T-crossmatch were identified to be at an increased risk for the development of a de novo malignancy.

Antibodies, Monoclonal↗

PubMed1993

Impact of clinical trial protocols on patient care systems at the University of Texas M.D. Anderson Cancer Center.

Clinical trial protocols represent a significant component of the research program at the University of Texas M.D. Anderson Cancer Center. Currently, there are nearly 800 active protocols using more than 150 investigational drugs. Sponsors of these trials include the National Cancer Institute, numerous pharmaceutical companies, and a variety of other funding sources. Because of our large patient base, however, routine participation in cooperative groups is limited. The impact of clinical trial protocols on patient care systems is a growing concern that is addressed primarily by the Surveillance Committee at M.D. Anderson. Like many institutional review boards, this committee reviews all protocols and must grant approval before the activation of any clinical trial. The issues of medical ethics, including a risk-benefit assessment for research subjects, equitable patient selection, safeguards for economically disadvantaged populations, and the general requirements for informed consent, also fall under the purview of this board. For any comprehensive cancer center to succeed, it must have strong research programs that enhance treatment options for patients. The crisis in financing health care significantly threatens the viability of cancer research. Reimbursement for the related costs of individuals participating in clinical trials has become a battle ground for third-party payers. The resulting economic risk is shared by health care providers and patients. As a consequence, many cancer centers, including M.D. Anderson, have initiated an economic-impact analysis for protocols as a component of the review process. This analysis includes an estimation of the patient care costs compared to the funding allocated to support the research. Future research will include pharmacoeconomic analysis and other ways to relate the costs and outcomes of treatment protocols. In the interim, we must monitor reimbursement trends for patients enrolled in clinical trials closely and amend the informed consent process to include a discussion of potential economic risk or hardship to patients if insurance claims are denied. Cancer care providers, third-party payers, the federal government, and society at large must work together to address the funding of cancer research and patient care.

Cancer Care Facilities↗

PubMed2001

Effects of digestion protocols on the isolation and characterization of metal-metal wear particles. II. Analysis of ion release and particle composition.

The isolation of metal wear particles from hip simulator lubricants is important for understanding wear mechanisms and the tissue response to particulate material. Part I of this study demonstrated that isolation protocols involving digestion reagents can chemically attack metal-metal wear particles, reducing their size and changing their shape. In part II of this study, Co and Cr ion concentrations in solution after each digestion protocol were measured by flame atomic absorption spectrometry, and wear particle composition was determined by X-ray analysis spectra. The exposure of wear particles in water to alkaline solutions caused an increasing release of Cr ions in solution with alkaline concentration and time, and a corresponding decrease in particle Cr peak intensity on X-ray spectra. As a result, particles exposed to 12N KOH for 48 h displayed Co peaks and no Cr. In contrast, enzymatic protocols caused a release of Co ions in solution and a corresponding decrease in particle Co peak intensity on X-ray spectra, especially with sodium phosphate as a buffer. However, when isolating particles from 95% serum, there was an initial protective effect of serum proteins, presumably because of their binding to Co and Cr. As a result, the extent of Cr ion release from metal wear particles in 95% serum after alkaline treatments was diminished, although still present, whereas both enzymatic protocols resulted in a negligible release of Co and Cr ions into solution. Particle composition analysis after enzymatic treatments revealed the presence of chromium oxide particles and CoCrMo particles with variable Co/Cr ratios. After alkaline treatments, the chromium oxide particles increasingly disappeared with time and alkaline concentration, demonstrating a change in particle composition after these treatments. This study demonstrated that digestion reagents can induce chemical changes that affect particle composition. Of all the protocols tested, the enzymatic protocols were the least damaging to the particles and appeared to be the best compromise for isolation and characterization of metal particles, especially in 95% serum. Special care on the choice of buffers should be taken when isolating particles from a lower concentration of serum.

Animals↗

PubMed2002

Selection of lymphocyte gating protocol has an impact on the level of reliability of T-cell subsets in aging specimens.

BACKGROUND: In the past decade, human immunodeficiency virus (HIV) lymphocyte immunophenotyping has evolved significantly. New fluorochromes, new multicolor reagents, enhanced instruments, and the capacity to provide absolute cell counts using the single-platform technique have all contributed to the reliability of T-cell subset measurements. In this study, four gating protocols were evaluated to select the most robust method for T-cell subset enumeration. METHODS: Peripheral blood specimens from 21 HIV(+) and 20 HIV(-) individuals were monitored up to 96 h. Aliquots of specimens were stored at room temperature and analyzed at 6 (baseline), 48, 72, and 96 h. Aliquots were stained with CD45-fluorescein isothiocyanate (FITC)/CD3PC5/CD4RD1/CD8ECD. Data analysis was performed with all four gating protocols. RESULTS: Only with fresh blood did all protocols provide similar results. From samples that were 48 h old, the choice of gating strategy had a dramatic impact on immunophenotyping results. The largest deviations from baseline values occurred at 96 h and gating protocols that included dual light scatter gates provided the greatest shift of T-cell subset values over time. The gating protocols that were based exclusively on cell lineage-specific gates gave the most robust T-cell values up to 96 h. CONCLUSION: By selecting the appropriate gating protocol, the temporal integrity of specimens can be extended up to 4 days.

Acquired Immunodeficiency Syndrome↗

PubMed2006

Report on a multicenter fMRI quality assurance protocol.

Temporal stability during an fMRI acquisition is very important because the blood oxygen level-dependent (BOLD) effects of interest are only a few percent in magnitude. Also, studies involving the collection of groups of subjects over time require stable scanner performance over days, weeks, months, and even years. We describe a protocol designed by one of the authors that has been tested for several years within the context of a large, multicenter collaborative fMRI research project (FIRST-BIRN). A full description of the phantom, the quality assurance (QA) protocol, and the several calculations used to measure performance is provided. The results obtained with this protocol at multiple sites over time are presented. These data can be used as benchmarks for other centers involved in fMRI research. Some issues with the various protocol measures are highlighted and discussed, and possible protocol improvements are also suggested. Overall, we expect that other fMRI centers will find this approach to QA useful and this report may facilitate developing a similar QA protocol locally. Based on the findings reported herein, the authors are convinced that monitoring QA in this way will improve the quality of fMRI data.

Brain Mapping↗

PubMed2002

New and better protocols for a short-term Caco-2 cell culture system.

The aim of the present study was to develop new and better protocols for a short-term Caco-2 cell culture system for use in rapid screening of intestinal drug absorption. Caco-2 cells were cultured according to several protocols for short-term cell culture to obtain monolayers. The effects of serum (fetal bovine serum, FBS) in the culture medium and of the period of cell culture on the barrier function and transporter activities of the monolayers were examined. The barrier function was estimated both from the transepithelial electrical resistance (TEER) and the permeability of [(14)C]mannitol. Transporter activities were monitored by measuring the permeability of [(14)C]glycylsarcosine for oligopeptide transporter (PepT1) and of rhodamine 123 for P-glycoprotein (P-gp). Caco-2 monolayers obtained by 3-day culture in the BIOCOAT HTS Caco-2 Assay System, developed by Becton Dickinson Bioscience, showed much higher permeability to hydrophilic compounds, such as mannitol, compared with those obtained by the standard 21-day culture system, due to the leaky structure of cell junctions. The newly developed 3-day protocol, which includes 10% FBS in the culture medium during the first day of culture, markedly enhanced TEER and lowered mannitol permeability of the monolayers. This protocol allowed us to better determine the rank order of permeability of compounds, giving results equivalent to those in the 21-day culture system. The longer culture period gave tighter monolayers, and the maximum value of TEER was obtained with 5 days in culture. However, after 5 days in culture, the integrity of monolayers decreased gradually. The highest activities of transporters, PepT1 and P-gp, in monolayers were obtained at days 5 or 6 of culture by the new protocol with FBS-containing medium. These results indicate that by a simple modification of the short-term culture protocol, it is possible to obtain Caco-2 monolayers with better barrier properties and higher activity of transporters that are equivalent to those found in the 21-day Caco-2 culture system.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed1988

Optimization of MR protocols: a statistical decision analysis approach.

A new method of optimizing MRI data acquisition protocols is presented. Tissues are modeled with probability density functions (PDFs) of tissue parameter values (such as T1, T2). The imaging data acquisition process is modeled as a mapping from a tissue parameter space to a signal strength space. Tissue parameter PDFs are mapped to signal strength PDFs for each tissue in a clinical problem. The efficacy of an MRI protocol is evaluated using the methods of statistical decision analysis applied to the signal strength PDFs, including the propagation of noise. This procedure evaluates the ability to discriminate different tissues based on the signal strengths produced with the protocol. The model can incorporate an arbitrary number of tissues, parameters, and pulse sequences in the protocol. The multivariate nature of MRI and the observed broad distribution of tissue parameter values makes this model more appropriate for optimizing data acquisition protocols than methods which maximize the signal-difference-to-noise ratio between discrete values of the tissue parameters. It is shown that these two methods may calculate different optimal protocols. The method can be used to optimize data acquisition for quantitative computer-based tissue classification, as well as imaging. Data acquisition and image processing philosophies are discussed in light of the method.

Computer Simulation↗

PubMed1994

Evaluation of two gonadotropin-releasing hormone (GnRH) analogues (leuprolide and buserelin) in short and long protocols for assisted reproduction techniques.

PURPOSE: The administration of two GnRH analogues (buserelin and leuprolide acetate) in long and short protocols was evaluated prospectively. In the long protocol, the analogues were given from day 1 of the cycle for at least 14 days and then hMG administration was started, while in the short protocol the analogues were initiated from cycle day 1, adding hMG from day 3. The patients were divided into four groups according to the protocol used: Group I, buserelin-long; Group II, buserelin-short; Group III, leuprolide-long; and Group IV, leuprolide-short. Serum E2 levels on the day of hCG injection and the number of follicles observed, oocytes retrieved, and embryos obtained, as well as implantation rates, were significantly higher (P < 0.001) in the long protocols than in the short ones. RESULTS: Pregnancy rates were similar in all groups, although a trend for better results was observed in buserelin-long compared to buserelin-short. There were no differences in the results achieved with buserelin or leuprolide. CONCLUSION: The administration of GnRH analogues (buserelin and leuprolide acetate) in long protocols induced a more intense ovarian response and was associated with significantly higher implantation rates and also a trend for higher pregnancy rates, although this difference was not statistically significant.

Adult↗

PubMed2003

Viability of basidiomycete strains after cryopreservation: comparison of two different freezing protocols.

The viability of 250 basidiomycete strains was determined after a 2-d and then after a 2-year storage under liquid nitrogen using two different freezing protocols. Using an original agar plug protocol (OP), 162 strains (65%) of the 250 strains survived a 2-d storage and 158 strains (63%) survived a 2-year storage in liquid nitrogen. Using a straw protocol (CP), 246 strains (98%) of the 250 strains survived a 2-d storage and 243 strains (97%) a 2-year storage in liquid nitrogen. In addition, other 106 strains were newly estimated using the CP protocol; 104 (98%) of them survived successfully a 2-d storage and 101 (95%) of them survived a 2-year storage in liquid nitrogen. The results indicate that the protocol used for cryopreservation can significantly influence strain survival. Markedly better results were obtained using the CP protocol.

Basidiomycota↗

PubMed2001

Feasibility of a short acquisition protocol for whole-body positron emission tomography with fluorine-18 fluorodeoxyglucose.

The conventional protocol for whole-body positron emission tomography (PET) with fluorine-18 fluorodeoxyglucose (FDG) requires a total acquisition time of 40-60 min, which is inconvenient for many oncological patients owing to fatigue and discomfort. This study examined the feasibility of a short protocol for whole-body PET. A phantom containing six "hot" spheres of gradually increasing diameter (10-38 mm) was imaged using a dedicated PET scanner for 20, 40, 60, 80, 120 and 600 s at various count rates. Thirty-four patients with various neoplasms underwent whole-body emission scans for 1 min per bed position 1 h after intravenous injection of 370 MBq of FDG (short protocol). A standard simultaneous transmission-emission acquisition for 10 min per bed position was performed thereafter. The images were reconstructed using an iterative algorithm. At a count rate of 40 kcps, which is close to the average count rate obtained in a whole-body FDG PET study, the 60-s image visualised five spheres, of which the smallest was 13 mm in size. Despite the better image quality, lesion detection was not improved in images acquired for more than 60 s (80-600 s). Only three of the six spheres could be detected in images acquired for less than 60 s. In the patient study, the standard protocol visualised 120 tumour lesions, of which 93 (78%) could be detected using the short protocol. Among the non-visualised lesions, 22 (82%) were < or =1.5 cm in size and 17 (63%) were lymph nodes. It is concluded that the proposed short protocol for whole-body FDG PET has a reasonably high detection rate and may be suitable for patients who are unable to undergo scanning for a prolonged period. It may also be useful as a pre-scan guide before a standard whole-body acquisition.

Adult↗

PubMed2005

Readmission and mortality in patients undergoing off-pump coronary artery bypass surgery with fast-track recovery protocol.

The development of less invasive methods for myocardial revascularization such as "off-pump" cardiac surgery, and new methods of anesthesia and postoperative care protocols such as "fast-track recovery" (FTRC), have contributed to a significant reduction in postoperative intensive care unit (ICU) and hospital length of stay after cardiac surgical procedures. The objectives of this study were to identify perioperative risk factors of prolonged hospital stay, hospital mortality, and readmission rates in off-pump coronary artery bypass surgery (CABG) patients undergoing the FTRC protocol. Eighty consecutive patients undergoing off-pump coronary artery bypass surgery with FTRC protocol were included in the study. For the first purpose of this protocol, early extubation is defined as removal of the endotracheal tube within 6 h of arrival at the surgical ICU. The second purpose was to obtain a minimal length of stay in the ICU (<24 h) and hospital discharge within 5 days. We analyzed the influence of the preoperative, intraoperative, and postoperative variables on prolonged hospital stay, hospital mortality, and hospital readmission. Three patients died during hospitalization, giving a hospital mortality rate of 3.75%. The causes of hospital death were massive stroke and sepsis. Using multivariate logistic regression analysis, hypertension (P = 0.0185), postoperative stroke (P = 0.0001), and sternal infection (P = 0.0007) were identified as independent predictors of hospital mortality. Mean hospital length of stay was 4.23 +/- 0.75 days. Univariate and multivariate logistic regression analysis revealed that postoperative blood use (P = 0.0095) was the major independent predictor of prolonged hospital stay. During the 30-day observation period, seven patients were readmitted. One of these patients died on postoperative day 45 from mediastinitis and sepsis. Multivariate logistic regression analysis identified age (P = 0.0033) and hypertension (P = 0.045) as independent predictors of hospital readmission. FTRC protocols can be performed safely in patients with off-pump CABG, and the mortality and readmission rates following this protocol were found to be within acceptable ranges.

Adult↗

PubMed2003

Increased recognition of type II endoleaks using a modified intraoperative angiographic protocol: implications for intermittent endoleak and aneurysm expansion.

Retrograde arterial perfusion of the aneurysm sac (type II endoleak) may complicate endovascular abdominal aortic aneurysm (AAA) repair and may lead to AAA expansion and rupture. Aneurysm expansion may also occur in the absence of a demonstrable endoleak. Current intraoperative assessment techniques may underrepresent the incidence of type II endoleaks. This study evaluated the incidence and impact of previously unrecognized type II endoleaks using a modified intraoperative angiographic protocol. A total of 391 patients undergoing endovascular AAA repair were evaluated. In 264 patients standard completion angiograms were performed. In 127 patients a modified angiographic protocol was used to visualize collateral lumbar and inferior mesenteric arteries as well as the aneurysm sac. The modified protocol uses digital subtraction fluoroscopy continuously for 60 sec after injections of 20 mL iodinated contrast both in the pararenal aorta and within the endovascular graft. Postoperative CT scans were performed at 1, 6, and 12 months and annually thereafter. The average age was 73.3 years; 324 patients were men and 67 were women. Mean follow-up was 11.4 months (range, 1-60 months). Type II endoleaks were documented intraoperatively in a significantly increased proportion of patients in whom the modified angiographic protocol was used: modified, 53/127 = 41% vs. standard, 17/264 = 6%; p < 0.001. No significant difference in the incidence of type II endoleaks was present on CT scan at 6 or 12 months after surgery (6 months: modified, 6/72 = 8% vs. standard, 10/159 = 6%, p = NS; 12 months: modified, 2/36 = 5% vs. standard, 6/138 = 4%, p = NS). Forty-six type II endoleaks resolved spontaneously (10 in the standard cohort, 36 in the modified cohort). One patient had a 10-mm increase in AAA diameter after spontaneous thrombosis of a type II endoleak 18 months postoperatively. One patient had a type II endoleak intraoperatively and at 12 months after surgery but the endoleak was absent at 1 and 6 months. Thirteen patients from the standard protocol cohort and 1 from the modified protocol cohort developed newly visualized type II endoleaks during follow-up. These findings may imply intermittent patency of the artery supplying the type II endoleak. The overall morbidity rate was 14% and the perioperative mortality rate was 1.8%. Retrograde (type II) endoleaks originating from AAA side branches occur intraoperatively more frequently than is currently recognized. Intermittent patency and thrombosis of these vessels may also occur and may contribute to AAA expansion. The full significance of these previously unrecognized endoleaks with respect to risk of aneurysm rupture remains to be definitively determined.

Aged↗

PubMed2006

MDCT for suspected pulmonary embolism: multi-institutional survey of 16-MDCT data acquisition protocols.

The purpose of this study was to determine the extent to which a consensus exists on multidetector row computed tomography (MDCT) protocol parameters for suspected pulmonary embolism (PE). In August of 2004, a questionnaire addressing a number of body MDCT protocols was mailed to 99 fellows of the Society of Computed Body Tomography, representing a total of 46 institutions. In May 2005, this was followed up with a second mailing. The survey requested details pertaining to protocols for the most advanced MDCT scanner in the department. The overall survey response rate of 37% (17/46) yielded 15 protocols for 16-MDCT imaging of suspected PE. This data was tabulated and revealed a consensus for the use of bolus tracking, rapid contrast infusion, caudo-cranial scanning, the narrowest detector row collimation, and thin (<2 mm) reconstruction sections. However, contrast infusion timing, contrast concentration, and implementation of radiation dose modulation were variable. This compilation of protocols reflects recently published studies advocating the use of narrow acquisition collimation and reconstruction sections for MDCT of suspected PE. Future studies are necessary to elucidate the optimal intravenous contrast infusion parameters and further assess the efficacy of reduced radiation dose protocols.

Consensus↗

PubMed2005

Comparison of maturation, meiotic competence, and chromosome aneuploidy of oocytes derived from two protocols for in vitro culture of mouse secondary follicles.

PURPOSE: To compare maturation rates of mouse preantral follicles cultured using two previously reported follicle in vitro follicle culture protocols, and to compare the aneuploidy of oocytes derived from the two protocols with in vivo-matured control oocytes. METHODS: Mouse preantral follicles were either mechanically isolated then cultured in individual microdroplets, or enzymatically isolated and cultured in groups in a modified culture medium. Maturation of the follicles/oocytes and resulting oocyte aneuploidy rates were evaluated and compared. RESULTS: The mechanical isolation and individual culture protocol (M/I) resulted in higher follicle survival than the enzymatic isolation and group culture protocol (E/G) (89.1% versus 79.1%, p < 0.01), and better maturation to the metaphase 2 stage (61.5% versus 39.5%, p = 0.01) The rate of aneuploidy of oocytes not significantly higher in oocytes from the E/G group than the M/I group (15.4% versus 9.9%), but hypoploidy was significantly increased (4.7% versus 0.9%, p < 0.05). Both groups had a higher rate of aneuploidy than the control oocytes (2.9%, p < 0.02). CONCLUSIONS: These results indicate an increased survival and competency of oocytes derived from the M/I protocol, compared to the E/G protocol. The data highlight an increased susceptibility to meiotic errors in early stage follicles undergoing in vitro culture, compared to in vivo-matured oocytes.

Aneuploidy↗

PubMed2006

Preliminary examination to determine the suitable contrast material injection protocol for CT angiography of the pelvis and lower extremities with a multidetector row helical scanner.

PURPOSE: The aim of this study was to determine the best of three protocols for the depiction of arteries in the pelvis and lower extremities by computed tomographic angiography (CTA) with a multidetector row helical scanner. MATERIALS AND METHODS: CTA was performed in five asymptomatic volunteers using a four-channel multidetector row helical scanner. Low-osmolar iodinated contrast material was injected at the flow rate of 3 ml/s using three protocols: 100 ml of 300 mg I/ml, 150 ml of 300 mg I/ml, and 100 ml of 350 mg I/ml. The CT number of opacified blood was measured at six levels. Three doctors independently assessed the degree of depiction of arteries on CTA images without knowing the protocol using a 3-point scale. RESULTS: CT numbers at the level of the popliteal artery on the protocol of 150 ml of 300 mg I/ml were significantly greater than the others. The mean score for the depiction of trifurcation on the protocol of 150 ml of 300 mg I/ml was significantly greater than those in the others. CONCLUSION: The protocol of 150 ml of 300 mg I/ml was the best for depicting arteries in the pelvis and lower extremities by CTA.

Adult↗

PubMed1991

The ventilatory threshold: method, protocol, and evaluator agreement.

To evaluate the effects of different methods of detection, exercise modes, protocols, and reviewers on oxygen uptake (VO2) at the ventilatory threshold (ATge), 17 men with heart disease (mean age 59 +/- 6 years) and six healthy men (mean age 60 +/- 11 years) underwent six exercise tests on different days. Each subject performed three treadmill tests (Bruce, Balke, and ramp) and three bicycle ergometer tests (50 W/stage, 25 W/stage, and ramp) in random order. The ventilatory threshold was determined for each of the six exercise tests by three independent, blinded reviewers by means of graphic plots of three commonly used methods of determination: (1) changes in the ventilatory equivalents for VO2 and VCO2, (2) changes in end-tidal oxygen and carbon dioxide pressures, and (3) the intersection of the slope of VCO2 and VO2 (V slope). The largest variability in the ATge was observed with changes in the exercise protocol. The greatest absolute (ml/min) and percentage differences in oxygen uptake at the ATge as a result of changes in protocol, method of determination, and observers were 336 (36%), 125 (12%), and 70 (7%), respectively. The overall intraclass correlation coefficient for VO2 at the ATge among the three reviewers was 0.60 and among the three protocols was 0.85 (p less than 0.01). The V slope method of detection had consistently good agreement among reviewers and was least affected by the protocol. The variance in the ATge (excluding intersubject and error variance) accounted for by differences in protocol, method, and reviewer was 82%, 14%, and 4%, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Anaerobic Threshold↗

PubMed1986

Evaluation of protocols for purification of mouse monoclonal antibodies. Yield and purity in two-dimensional gel electrophoresis.

Protocols for purification of mouse monoclonal antibodies (MAbs) from nude mice ascites were investigated in order to assess the yield and to compare the purified products in two-dimensional gel electrophoresis (2DGE). Three MAbs (one IgG2 and two IgG1), selected for their differing behaviours towards protein A, were purified by ammonium sulphate precipitation and/or gel filtration, anion exchange (DEAE), hydroxylapatite and affinity (protein A) chromatography, or by a combination of these methods. Protein A constantly provided the highest purity whatever the IgG subclass. The best results in terms of yields and purity were a function of the optimization of the protein A protocol. In our study, they were obtained in a 3 h protocol (IgG2), a 16 h protocol with discontinuous pH gradient method (IgG1 with sufficiently high affinity for protein A) or a multi-step protocol involving DEAE and protein A (IgG1 with low affinity for protein A). DEAE chromatography alone provided a slightly better yield, but only moderate purity. Hydroxylapatite chromatography appeared to be less potent in terms of yield, purity and day-to-day reproducibility. Salt precipitation and gel filtration enabled only relative enrichment of the MAb solution. Some degradation products of both heavy and light chains clearly appeared in the 2DGE patterns of antibodies purified by different protocols, and seem to be partly related to the elution pH and to the duration of the purification procedure. Finally, this work highlights considerable heterogeneity not only between two different MAbs of the IgG1 subclass but also within a monoclonal population of immunoglobulins.

Ammonium Sulfate↗