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PubMed1981

Early load-limiting versus symptom-limited exercise testing: prognostic value in 200 myocardial infarction patients.

The prognostic value of early load-limited and symptom-limited exercise testing has been compared in 200 men younger than 65 years of age, after myocardial infarction. 164 patients performed both tests and in 79 of the 200 cases who performed the early test the result was positive (40%); the percentage of positive tests was higher with the symptom-limited test (53.6%). The prognostic value of both tests was high. During the follow-up the mortality rate was higher in patients with positive results, but the early test enables the identification of patients in a higher risk group before hospital discharge.

Adult↗
PubMed1980

Symptom-limited vs heart-rate-limited exercise testing soon after myocardial infarction.

To develop guidelines for exercise testing soon after uncomplicated myocardial infarction, 93 men completed a heart-rate-limited (HRL) protocol and 107 completed a symptom-limited (SXL) protocol 3 weeks after the acute event. In the HRL protocol, effort terminated at a heart rate of 130 beats/min in the absence of a limiting symptom, exertional hypotension or ventricular tachycardia. Peak heart rate was not an end point in the SXL protocol. Despite a higher peak heart rate and work load in patients who completed the SXL protocol, the prevalence of exercise-induced ischemic ST-segment depression and ventricular ectopic activity was similar in the two groups. No complications occurred with either protocol. Twelve patients (6%) had cardiac events within the next 2 months. Regardless of the test protocol used, early events were more common in patients with ischemic ST-segment responses (15%) than in patients without ischemic responses (3%) (p less than 0.01). In contrast, exercise-induced ventricular arrhythmias were not predictive of early events. Eleven weeks after infarction, when all tests were SXL, the prevalence of exercise-induced ischemic ST-segment depression and premature ventricular complexes was similar to that at 3 weeks. We conclude that SXL and HRL exercise test protocols reveal a similar prevalence of ischemic ST-segment depression and ventricular ectopic activity soon after uncomplicated myocardial infarction.

Angina Pectoris↗
PubMed1992

Amino acid limitation and flow to the duodenum at four stages of lactation. 2. Extent of lysine limitation.

Four multiparous Holstein cows with ruminal and duodenal cannulas were assigned to 4 x 4 Latin squares at peak (wk 4), early (wk 14 to 16), mid (wk 21 to 23), and late (wk 29 to 31) lactation to determine, in the presence of supplemental Met, the extent of Lys limitation and its required contribution to total essential AA in duodenal digesta. Treatments were duodenal infusions of 1) water alone or water with 2) 10 g/d of DL-Met plus 10 g/d of L-Lys, 3) 10 g/d of Met plus 20 g/d of Lys, and 4) 10 g/d of Met plus 30 g/d of Lys; quantities were reduced by 20% in late lactation. Rations were corn based (corn and grass-legume silages, corn meal, wheat middlings, soybean meal, and distillers dried grains with solubles) and most limiting in Lys and Met. Intakes of ruminally degraded and undegraded intake protein (percentage of NRC requirements) were (peak) 115, 97; (early) 112, 83; (mid) 113, 87; and (late) 127, 96. Contribution of Lys to passage of total essential AA to the duodenum without infusions were 13.2, 12.4, 13.8, and 14.8% at the four respective stages of lactation. Extent of Lys limitation determined from responses in content and yield of milk protein approximated 25, 20, and 10 g/d during peak, early, and midlactation.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acids↗
PubMed2005

Screening of brain metastasis with limited magnetic resonance imaging (MRI): clinical implications of using limited brain MRI during initial staging for non-small cell lung cancer patients.

The purpose of this prospective study was to determine whether using magnetic resonance imaging (MRI) for early screening for brain metastases (BM) can improve quality of life, survival in patients with non-small cell lung cancer (NSCLC). The study group comprised 183 patients newly diagnosed with NSCLC. All patients underwent limited brain MRI and routine workups. The control group comprised 131 patients with NSCLC who underwent limited brain MRI only if they had neurologic symptoms. The incidence of BM was 20.8% (38/183) in the study group and 4.6% (6/131) in the control group. The rate of upstaging based on the MRI data was 13.5% (15/111) overall and 15.9% (11/69) in patients that had been considered initially to be resectable surgically. There was no significant difference in survival outcome between the groups. Patients who had BM alone had a greater overall survival time (49 weeks) than those who had multiple systemic metastases (27 weeks; p=0.0307). In conclusions, limited brain MRI appears to be a useful, cost-effective method to screen for BM at the time of initial staging. And it may facilitate timely treatment of patients with NSCLC and improve their survival and quality of life.

Adult↗
PubMed1993

Medicaid program; limitations on provider-related donations and health care-related taxes; limitations on payments to disproportionate share hospitals--HCFA. Final rule.

This final rule clarifies HCFA's policies concerning provider related donations and health care related taxes. In addition, this final rule revises regulations with regard to disproportionate share hospital spending limitations. This final rule amends an interim final rule that was published in the Federal Register on November 24, 1992. The interim final rule established in Medicaid regulations limitations on Federal financial participation (FFP) in State medical assistance expenditures when States receive funds from provider-related donations and revenues generated by certain health care-related taxes. The interim final rule also added provisions that establish limits on the aggregate amount of payments a State may make to disproportionate share hospitals for which FFP is available. The provisions of the interim final rule were required by the Medicaid Voluntary Contribution and Provider Specific Tax Amendments of 1991.

Centers for Medicare and Medicaid Services, U.S.↗
PubMed1975

[Theoretical basis of the search of individual limits of fluctuations and the maximum long-term maintainance of arterial pressure within the maximum permissible limits in hypotensive therapy].

The methods of determining the maximum permissible and functionally justifiable (upper and lower) limits of arterial pressure fluctuations limiting the zones of individual "comfort" "caution" and "alarm" for every patient are described. The mathematical method of the least squares was used for long-term control of the maintenance of arterial pressure within the limits individually pre-set for those treated on an out-patient basis. The above methods permit to decrease the duration of therapy with a minimal drug expenditure and to ensure a mass control of the efficacy of hypotensive therapy.

Antihypertensive Agents↗
PubMed2006

Comparison of fixed percentage method and lower confidence limits for defining limits of normality for interpretation of spirometry.

BACKGROUND: The use of the lower 90% confidence limit of the lower limit of normal (LLN(CI)), rather than a fixed percentage of the predicted value (LLN(%)), appears to be statistically more appropriate for interpretation of spirometry results. There has been no comparative assessment of these 2 definitions of the LLN in routine clinical practice. METHODS: We studied results of spirometry interpretations made with these 2 approaches, and assessed various factors that influence discordant classification of spirometry results. Spirometry records from 18,112 consecutive adult patients referred for spirometry were interpreted as normal, obstructive, or restrictive, based on both LLN(CI) and LLN(%). Discordant results were analyzed using multiple logistic regression techniques to identify variables that significantly affected discordant classification of results. RESULTS: Overall, 11.7% of the results were discordant between the 2 methods. Agreement between the 2 methods, calculated using the kappa estimate, was poorer with spirometry values from women and from patients at the extremes of height and age. Age, sex, and height independently influenced discordant classification. Limits of agreement between LLN(CI) and LLN(%) were wide for all the spirometric variables studied--more so in women and in shorter and older patients. CONCLUSIONS: LLN(CI) and LLN(%) yielded different interpretations of spirometry data in several instances, and the 2 methods cannot be used interchangeably. When interpreting spirometry data in routine clinical practice, LLN(CI) should be preferred over LLN(%).

Adolescent↗
PubMed1981

[Limits of resuscitation. I. Thanatophysiologic and therapeutic limits].

Neither apodictic demands nor administration measures are suited to satisfy the various problems of the duty of treatment in the borderline region between life and death. An exact knowledge of the thanatophysiologic limits of the possibility of resuscitation during and after an anoxia and ischaemia is necessary. By effective cardiopulmonary measures of resuscitation, such as external heart massage with production of systolic pressure of 8-13 kPa as well as respiration with F1O2 1.0, the cardiac resuscitation time with immediate sufficiency (1. limit 4-41/2 min) may be prolonged to the cerebral resuscitation time from 8-10 minutes. Probably, the new concept of specific measures of cerebral resuscitation may definitively prolong also this 2nd limit. Furthermore, the fundamentals of the decision are discussed, for omitting or finishing a reanimation, or for reducing the intensive treatment. If the clinical syndrome of the dissociated cerebral death is present, without planned taking off an organ there is no necessity to render the finish of the intensive therapy dependent on legal regulations concerning the performance of organ transplantations.

Attitude to Death↗
PubMed2001

Double-blind, randomized trial of an anti-CD18 antibody in conjunction with recombinant tissue plasminogen activator for acute myocardial infarction: limitation of myocardial infarction following thrombolysis in acute myocardial infarction (LIMIT AMI) study.

BACKGROUND: Inhibition of leukocyte adhesion can reduce myocardial infarct size in animals. This study was designed to define the safety and efficacy of a recombinant, humanized, monoclonal antibody to the CD18 subunit of the beta2 integrin adhesion receptors (rhuMAb CD18), in reducing infarct size in patients treated with a thrombolytic agent. METHODS AND RESULTS: The Limitation of Myocardial Infarction following Thrombolysis in Acute Myocardial Infarction Study (LIMIT AMI) was a randomized, double-blind, placebo-controlled, multicenter study conducted in 60 centers in the United States and Canada. A total of 394 subjects who presented within 12 hours of symptom onset with ECG findings (ST-segment elevation) consistent with AMI were treated with recombinant tissue plasminogen activator and were also given an intravenous bolus of 0.5 or 2.0 mg/kg rhuMAb CD18 or placebo. Coronary angiography was performed at 90 minutes, 12-lead ECGs were obtained at baseline, 90, and 180 minutes, and resting sestamibi scans were performed at >/=120 hours. Adjunctive angioplasty and use of glycoprotein IIb/IIIa antiplatelet agents at the time of angiography were discretionary. There were no treatment effects on coronary blood flow, infarct size, or the rate of ECG ST-segment elevation resolution, despite the expected induction of peripheral leukocytosis. A slight trend toward an increase in bacterial infections was observed with rhuMAb CD18 (P=0.33). CONCLUSIONS: RhuMAb CD18 was well tolerated but not effective in modifying cardiac end points.

Antibodies, Monoclonal↗
PubMed1997

Determination of pharmaceuticals in plasma by capillary electrophoresis without sample pretreatment reproducibility, limit of quantitation and limit of detection.

Pharmaceuticals in human plasma are determined on underivatized fused-silica capillaries by micellar electrokinetic capillary chromatography (MEKC) without sample pretreatment. Our best method to date uses as running buffer a sodium dodecyl sulfate (SDS) containing borate buffer (60 mM with 200 mM SDS) at pH 10. Between runs, proteins adsorbed to the capillary wall are removed by an acetonitrile and SDS-buffer rinsing regimen (50% v/v each). A day-to-day precision for relative peak areas of about 2% relative standard deviation (RSD; n > 40) has been reached. Different rinsing approaches are discussed (salts, enzyme-containing solutions, organic solvents, hydrofluoric acid). The separation system is tested in a concentration range between approximately 100 mg/L-10 mg/L. Correlations between the limit of quantitation, the limit of detection and the signal/noise are discussed. The applicability of the system is demonstrated for the pharmaceuticals acetaminophen, salicylic acid, sulfamethoxazole, tolbutamide, and trimethoprim.

Acetaminophen↗
PubMed1998

Comparative mitogenic potencies of EGF and TGF alpha and their dependence on receptor-limitation versus ligand-limitation.

Transforming growth factor alpha (TGF alpha) has been reported to be a more potent agonist when compared to epidermal growth factor (EGF) in several systems while acting via their common receptor, the epidermal growth factor receptor (EGFR). It has been postulated that this increased potency is mediated by the increased recycling of EGFR upon activation by TGF alpha as against receptor activation by EGF. The authors test this hypothesis by simultaneously measuring mitogenesis and the dynamics of surface receptor number in response to these ligands in NR6 mouse fibroblasts expressing the EGFR. The data demonstrates that increased receptor recycling due to endosomal dissociation of TGF alpha can indeed realise an increased mitogenic potency relative to EGF under appropriate cellular and experimental conditions (i.e. situations in which the increase in the number of occupied receptors due to receptor sparing by TGF alpha represents additional mitogenic signalling capacity). However, this difference in receptor trafficking does not uniquely determine the relative potencies of these ligands since TGF alpha is a less potent mitogen compared to EGF when experimental conditions are dominated by the effects of ligand trafficking on growth factor availability. Thus, the relative potencies of these growth factors are determined in a given context by the relative importance of ligand and receptor trafficking effects which determine the availability of these signalling components. These results are consistent with a suggested model of hormone responsiveness which favours dissociative ligands (such as TGF alpha) in receptor-limited situations and non-dissociative ligands (such as EGF) in the case of ligand limitation.

Animals↗
PubMed1989

Future imperfect: the limitations of clinical prediction models and the limits of clinical prediction.

Stepwise regression procedures are often used to identify a small set of variables that serve as important predictors of clinical outcome and to construct prediction models based on those variables. Several theoretical and practical limitations of this process are discussed and highlighted with a variety of examples from published reports. Wider appreciation of these limitations should encourage the development of more relevant models, and thereby improve the quality of clinical prediction.

Models, Statistical↗
PubMed2000

Decay kinetics and quantum yields of fluorescence in photosystem I from Synechococcus elongatus with P700 in the reduced and oxidized state: are the kinetics of excited state decay trap-limited or transfer-limited?

Transfer and trapping of excitation energy in photosystem I (PS I) trimers isolated from Synechococcus elongatus have been studied by an approach combining fluorescence induction experiments with picosecond time-resolved fluorescence measurements, both at room temperature (RT) and at low temperature (5 K). Special attention was paid to the influence of the oxidation state of the primary electron donor P700. A fluorescence induction effect has been observed, showing a approximately 12% increase in fluorescence quantum yield upon P700 oxidation at RT, whereas at temperatures below 160 K oxidation of P700 leads to a decrease in fluorescence quantum yield ( approximately 50% at 5 K). The fluorescence quantum yield for open PS I (with P700 reduced) at 5 K is increased by approximately 20-fold and that for closed PS I (with P700 oxidized) is increased by approximately 10-fold, as compared to RT. Picosecond fluorescence decay kinetics at RT reveal a difference in lifetime of the main decay component: 34 +/- 1 ps for open PS I and 37 +/- 1 ps for closed PS I. At 5 K the fluorescence yield is mainly associated with long-lived components (lifetimes of 401 ps and 1.5 ns in closed PS I and of 377 ps, 1.3 ns, and 4.1 ns in samples containing approximately 50% open and 50% closed PS I). The spectra associated with energy transfer and the steady-state emission spectra suggest that the excitation energy is not completely thermally equilibrated over the core-antenna-RC complex before being trapped. Structure-based modeling indicates that the so-called red antenna pigments (A708 and A720, i.e., those with absorption maxima at 708 nm and 720 nm, respectively) play a decisive role in the observed fluorescence kinetics. The A720 are preferentially located at the periphery of the PS I core-antenna-RC complex; the A708 must essentially connect the A720 to the reaction center. The excited-state decay kinetics turn out to be neither purely trap limited nor purely transfer (to the trap) limited, but seem to be rather balanced.

Chlorophyll↗
PubMedDate not supplied

[the role of radiotherapy for limited stage Hodgkin's disease in 1999: limitations and perspectives].

The role of radiotherapy in limited stage Hodgkin's disease (HD) has been gradually changing in the past few decades, resulting in the almost complete disappearance of exclusive irradiation treatment. In reality, exclusive radiotherapy yielded satisfactory results in terms of long-term survival, but in 1999 it was becoming impossible not to take into account the late mortality rates observed in all large cohorts of HD patients. This increased mortality rate has been shown to be related to 1) cardiac toxicity of irradiation, and 2) secondary radiation-induced solid tumors. Thus, the search for efficient but less toxic new strategies can no longer be avoided. For clinically staged, limited HD, precisely defined according to specific prognostic factors, the association of chemotherapy and radiotherapy appears more and more as a standard, and with this therapeutic burden comes parallel efforts for its alleviation. The Previous Radiotherapy experience has shown that, after a chemotherapy-induced complete remission, irradiation of only the initially involved areas was enough. Ongoing trials are now exploring the possibility of a dose de-escalation, from the conventional 36 Gy to 20 Gy (as for children HD), and to maybe 0 Gy (no radiotherapy at all). In parallel, deescalation in the number of chemotherapy cycles is also being investigated. For unfavorable cases, the problem is slightly different, as a higher percentage of cases still appears to be refractory to treatment in this subgroup. Thus, while chemo-radiotherapy has clearly became the standard strategy, efforts are essentially being devoted to identify new--and hopefully more efficient--chemotherapy schemes. In Europe, most of these pending questions will be addressed in the recently initiated trials of the EORTC/GELA and of the GHSG (German Hodgkin Study Group), with the aim of offering to patients treatment which could be at least as efficient as the present schedules, and less toxic in the long term.

Cardiovascular System↗
PubMed2001

Transcription of cytokeratins 8, 18, and 19 in bone marrow and limited expression of cytokeratins 7 and 20 by carcinoma cells: inherent limitations for RT-PCR in the detection of isolated tumor cells.

The suitability of "real-time" quantitative reverse transcriptase polymerase chain reaction (RT-PCR) for the detection of isolated carcinoma cells in bone marrow was investigated by evaluating the expression of cytokeratin (CK)7, CK8, CK18, CK19, and CK20 in 17 gastrointestinal cancer cell lines, 64 control bone marrow specimens from noncancer patients, and 30 bone marrow specimens from patients with gastric or colorectal cancer. RT-PCR products for CK8 and CK18 were detected in all cancer cell lines, but only 16, 5, and 11 cell lines provided evidence for CK19, CK7, and CK20 transcription. Variable numbers of bone marrow specimens from noncancer patients demonstrated background transcription of CK8 (78.1%), CK18 (95.3%), CK19 (35.9%), CK20 (29.6%), and CK7 (16.7%). Maximal background transcription for CK8, CK18, and CK19 ranged from 52.2 to 56.1 copies/10(3) copies glyceraldehyde-3-phosphate dehydrogenase (GAPDH), the corresponding values of 0.06 and 0.76 copies for CK7 and CK20 being distinctly lower. When maximal background values were used as a threshold value to define positivity in tumor cell dilution experiments, sensitivity levels of one tumor cell in 10(4) bone marrow cells were determined for CK7 and CK20 RT-PCR assays. Maximal background expression values of the different CKs as obtained in the control series were exceeded once (CK20), twice (CK18 and CK19), and 18 times (CK7) in bone marrow specimens from cancer patients, with none of these specimens exceeding the maximal background expression value of CK8. We conclude that RT-PCR for CK8, CK18, and CK19 cannot be recommended for the detection of isolated tumor cells in bone marrow of cancer patients. On the other side, the limited number of gastric and colorectal cancer cell lines expressing CK7 and CK20 indicates that assay sensitivity for these CKs might be limited because of their selective expression by carcinoma cells.

Animals↗
PubMed1979

Limited proteolysis of complement components C2 and factor B. Structural analogy and limited sequence homology.

A method is described for the simultaneous purification of milligram quantities of complement components C2 and Factor B. Both products are homogeneous by the criteria of polyacrylamide-gel electrophoresis and N-terminal sequence analysis. Component C2 is cleaved by serine proteinase C1s at an X-Lys bond to give fragment C2a (approx. mol.wt. 74000) and fragment C2b (approx. mol.wt. 34000). The two fragments can be separated by gel filtration without the need for reducing or denaturing agents. Fragment C2b represents the N-terminal end of the molecule. Similar results were seen on cleavage of Factor B by Factor D in the presence of component C3. Again two non-covalently linked fragments are formed. The smaller, fragment Ba (approx. mol.wt. 36,000),) has threonine as the N-terminal residue, as does Factor B; the larger, fragment Bb (approx. mol. wt. 58000), has lysine as the N-terminal residue. A similar cleavage pattern is obtained on limited proteolysis of Factor B by trypsin, suggesting an Arg-Lys-or Lys-Lys bond at the point of cleavage. Although component C2 and Factor B show no apparent N-terminal sequence homology, a limited degree of sequence homology is seen around the sites of proteolytic cleavage.

Amino Acid Sequence↗
PubMed2002

Limiting metabolic rate (thermal work limit) as an index of thermal stress.

The development of a rational heat stress index called thermal work limit (TWL) is presented. TWL is defined as the limiting (or maximum) sustainable metabolic rate that euhydrated, acclimatized individuals can maintain in a specific thermal environment, within a safe deep body core temperature (< 38.20 degrees C) and sweat rate (< 1.2 kg/hr(-1)). The index has been developed using published experimental studies of human heat transfer, and established heat and moisture transfer equations through clothing. Clothing parameters can be varied and the protocol can be extended to unacclimatized workers. The index is designed specifically for self-paced workers and does not rely on estimation of actual metabolic rates, a process that is difficult and subject to considerable error. The index has been introduced into several large industrial operations located well inside the tropics, resulting in a substantial and sustained fall in the incidence of heat illness. Guidelines for TWL are proposed along with recommended interventions. TWL has application to professionals from both the human and engineering sciences, as it allows not only thermal strain to be evaluated,. but also the productivity decrement due to heat (seen as a reduced sustainable metabolic rate) and the impact of various strategies such as improved local ventilation or refrigeration to be quantitatively assessed.

Acclimatization↗
PubMedDate not supplied

Limitations on the uses of multimedia exposure measurements for multipathway exposure assessment--Part I: Handling observations below detection limits.

Multimedia data from two probability-based exposure studies were investigated in terms of how censoring of nondetects affected estimation of population parameters and associations. Appropriate methods for handling censored below-detection-limit(BDL)values in this context were unclear since sampling weights were involved and since bivariate associations/measures were of interest. Both simple substitution(e.g., using 1/2 or 2/3 of the detection limit(DL)for BDL values)and truncation-based strategies were investigated by creating some artificial DLs and comparing resultant estimates with the original studies'uncensored results. The substitution methods generally outperformed the truncation methods, with the(2/3)DL substitution generally performing best.

Child↗