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M Krol

Publications and source records attributed to M Krol.

At least 19 recordsLinked to original sources
PubMed2006

The global atmospheric environment for the next generation.

Air quality, ecosystem exposure to nitrogen deposition, and climate change are intimately coupled problems: we assess changes in the global atmospheric environment between 2000 and 2030 using 26 state-of-the-art global atmospheric chemistry models and three different emissions scenarios. The first (CLE) scenario reflects implementation of current air quality legislation around the world, while the second (MFR) represents a more optimistic case in which all currently feasible technologies are applied to achieve maximum emission reductions. We contrast these scenarios with the more pessimistic IPCC SRES A2 scenario. Ensemble simulations for the year 2000 are consistent among models and show a reasonable agreement with surface ozone, wet deposition, and NO2 satellite observations. Large parts of the world are currently exposed to high ozone concentrations and high deposition of nitrogen to ecosystems. By 2030, global surface ozone is calculated to increase globally by 1.5 +/- 1.2 ppb (CLE) and 4.3 +/- 2.2 ppb (A2), using the ensemble mean model results and associated +/-1 sigma standard deviations. Only the progressive MFR scenario will reduce ozone, by -2.3 +/- 1.1 ppb. Climate change is expected to modify surface ozone by -0.8 +/- 0.6 ppb, with larger decreases over sea than over land. Radiative forcing by ozone increases by 63 +/- 15 and 155 +/- 37 mW m(-2) for CLE and A2, respectively, and decreases by -45 +/- 15 mW m(-2) for MFR. We compute that at present 10.1% of the global natural terrestrial ecosystems are exposed to nitrogen deposition above a critical load of 1 g N m(-2) yr(-1). These percentages increase by 2030 to 15.8% (CLE), 10.5% (MFR), and 25% (A2). This study shows the importance of enforcing current worldwide air quality legislation and the major benefits of going further. Nonattainment of these air quality policy objectives, such as expressed by the SRES-A2 scenario, would further degrade the global atmospheric environment.

Air Pollutants↗
PubMed2006

Acclimation to temperature and irradiance modulates PSII charge recombination.

Acclimation of wild type and the chlorina F2 mutant of barley to either high light or low temperature results in a 2- to 3-fold increase in non-photochemical quenching which occurred independently of either energy-dependent quenching (qE), xanthophyll cycle-mediated antenna quenching or state transitions. Results of in vivo thermoluminescence measurements used to address this conundrum indicated that excitation pressure regulates the temperature gap for S(2)Q(B)(-) and S(2)Q(A)(-) charge recombinations within photosystem II reaction centers. This is discussed in terms of photoprotection through non-radiative charge recombination.

Acclimatization↗
PubMed2004

Application of fuzzy functions for visual presentation of medical data.

While interpretation of medical data is very often an ambiguous process, computers usually display results of recommendations, provided by both human experts and computer algorithms, as concrete data. This study proposes a visual presentation of relative degrees of uncertainty along with "standard" concrete medical data. A medical parameter (mean arterial pressure) is dynamically evaluated during surgery for being too low or too high. Fuzzy membership functions are utilized to display degrees of deviation in the form of a clear and concise pie chart. Thus, in the Operating Room the anesthesiologist can be provided with an easy statistical assessment of uncertainty of existing recommendations.

Algorithms↗
PubMed2001

Mouse BAC ends quality assessment and sequence analyses.

A large-scale BAC end-sequencing project at The Institute for Genomic Research (TIGR) has generated one of the most extensive sets of sequence markers for the mouse genome to date. With a sequencing success rate of >80%, an average read length of 485 bp, and ABI3700 capillary sequencers, we have generated 449,234 nonredundant mouse BAC end sequences (mBESs) with 218 Mb total from 257,318 clones from libraries RPCI-23 and RPCI-24, representing 15x clone coverage, 7% sequence coverage, and a marker every 7 kb across the genome. A total of 191,916 BACs have sequences from both ends providing 12x genome coverage. The average Q20 length is 406 bp and 84% of the bases have phred quality scores > or = 20. RPCI-24 mBESs have more Q20 bases and longer reads on average than RPCI-23 sequences. ABI3700 sequencers and the sample tracking system ensure that > 95% of mBESs are associated with the right clone identifiers. We have found that a significant fraction of mBESs contains L1 repeats and approximately 48% of the clones have both ends with > or = 100 bp contiguous unique Q20 bases. About 3% mBESs match ESTs and > 70% of matches were conserved between the mouse and the human or the rat. Approximately 0.1% mBESs contain STSs. About 0.2% mBESs match human finished sequences and > 70% of these sequences have EST hits. The analyses indicate that our high-quality mouse BAC end sequences will be a valuable resource to the community.

Animals↗
PubMed2000

Development of a decision support system to assist anesthesiologists in operating room.

The complexity of modern anesthesia procedures requires the development of decision-support systems functioning in a smart-alarm capacity. We developed computer algorithms to detect critical conditions during surgery (light anesthesia or unstable blood pressure), based on computerized anesthesia records containing hemodynamic data (heart rate, mean arterial pressure and systolic arterial pressure). Our analysis indicated that a > or = 12% change in mean arterial blood pressure (MAP), compared with the median value of MAP over the preceding 10-min interval, may be chosen as the criterion for detecting LA, with a sensitivity of 96% and a specificity of 91%. The best agreement between human and computer ratings of blood pressure lability (correlation coefficient 0.78) was achieved when we used the absolute value of the fractional change of the mean arterial pressure (magnitude of FCM) between one 2-min epoch and the next 2-min epoch. Work is under progress to develop a decision-support system to alert clinicians in the operating room environment to critical events.

Algorithms↗
PubMed2000

Arterial blood pressure and heart rate discrepancies between handwritten and computerized anesthesia records.

UNLABELLED: Previous publications suggest that handwritten anesthesia records are less accurate when compared with computer-generated records, but these studies were limited by small sample size, unblinded study design, and unpaired statistical comparisons. Eighty-one pairs of handwritten and computer-generated neurosurgical anesthesia records were retrospectively compared by using a matched sample design. Systolic arterial pressure (SAP), diastolic arterial pressure (DAP), and heart rate (HR) data for each 5-min interval were transcribed from handwritten records. In computerized records, the median of up to 20 values was calculated for SAP, DAP, and HR for each consecutive 5-min epoch. The peak, trough, standard deviation, median, and absolute value of the fractional rate of change between adjacent 5-min epochs were calculated for each case. Pairwise comparisons were performed by using Wilcoxon tests. For SAP, DAP, and HR, the handwritten record peak, standard deviation, and fractional rate of change were less than, and the trough and median were larger than, those in corresponding computer records (all with P: < 0.05, except DAP median and HR peak). Considering together all the recorded measurements from all cases, extreme values were recorded more frequently in computerized records than in the handwritten records. IMPLICATIONS: The discrepancies between handwritten and computerized anesthesia records suggest that some of the data in handwritten records are inaccurate. The potential for inaccuracy should be considered when handwritten records are used as source material for research, quality assurance, and medicolegal purposes.

Adolescent↗
PubMed1999

Object-oriented analysis and design of a health care management information system.

We have created a prototype for a universal object-oriented model of a health care system compatible with the object-oriented approach used in version 3.0 of the HL7 standard for communication messages. A set of three models has been developed: (1) the Object Model describes the hierarchical structure of objects in a system--their identity, relationships, attributes, and operations; (2) the Dynamic Model represents the sequence of operations in time as a collection of state diagrams for object classes in the system; and (3) functional Diagram represents the transformation of data within a system by means of data flow diagrams. Within these models, we have defined major object classes of health care participants and their subclasses, associations, attributes and operators, states, and behavioral scenarios. We have also defined the major processes and subprocesses. The top-down design approach allows use, reuse, and cloning of standard components.

Acute Disease↗
PubMed1999

Intraoperative hemodynamic predictors of mortality, stroke, and myocardial infarction after coronary artery bypass surgery.

UNLABELLED: Evidence that intraoperative hemodynamic abnormalities influence outcome is limited. The purpose of this study was to determine whether intraoperative hemodynamic abnormalities were associated with mortality, stroke, or perioperative myocardial infarction (PMI) in a large cohort of patients undergoing coronary artery bypass grafting. Risk factors and outcomes were queried from a state-mandated cardiac surgery reporting system at two hospitals in New York, NY. Intraoperative hemodynamic abnormalities were derived from computerized anesthesia records by assessing the duration of exposure to moderate or severe extremes of hemodynamic variables. Multivariate logistic regression identified independent predictors of perioperative mortality, stroke, and PMI. Among 2149 patients, there were 50 mortalities, 51 strokes, and 85 PMIs. In the precardiopulmonary bypass (pre-CPB) period, pulmonary hypertension was a predictor of mortality (odds ratio [OR] 2.1, P = 0.029), and bradycardia and tachycardia were predictors of PMI (OR 2.9, P = 0.007 and OR 2.0, P = 0.028, respectively). During CPB, hypotension was a predictor of mortality (OR 1.3, P = 0.025). Post-CPB, tachycardia was a predictor of mortality (OR 3.1, P = 0.001), diastolic arterial hypertension was a predictor of stroke (OR 5.4, P = 0.012), and pulmonary hypertension was a predictor of PMI (OR 7.0, P < 0.001). Increased pulmonary arterial diastolic pressure post-CPB was a predictor of mortality (OR 1.2, P = 0.004), stroke (OR 3.9, P = 0.002), and PMI (OR 2.2, P = 0.001). Rapid intraoperative variations in blood pressure and heart rate were not independent predictors of these outcomes. These findings demonstrate the prognostic significance of intraoperative hemodynamic abnormalities, including data from pulmonary artery catheterization, to adverse postoperative outcomes. It is not known whether interventions to control these variables would improve outcome. IMPLICATIONS: Intraoperative hemodynamic abnormalities, including pulmonary hypertension, hypotension during cardiopulmonary bypass, and postcardiopulmonary bypass pulmonary diastolic hypertension, were independently associated with mortality, stroke, and perioperative myocardial infarction over and above the effects of other preoperative risk factors.

Blood Pressure↗
PubMed1999

Beneficial effects from beta-adrenergic blockade in elderly patients undergoing noncardiac surgery.

BACKGROUND: Perioperative beta-blockade has been shown to improve long-term cardiac outcome in noncardiac surgical patients. A possible mechanism for the reduced risk of perioperative myocardial infarction is the attenuation of the excitotoxic effects of catecholamine surges by beta-blockade. It was hypothesized that beta-blocker-induced alteration of the stress response was responsible for the reported improvements in cardiovascular outcome. Several variables associated with the perioperative use of beta-blockade were also evaluated. METHODS: Sixty-three patients were randomly assigned to one of three groups: group I, no atenolol; group II, pre- and postoperative atenolol; group III, intraoperative atenolol. Hormonal markers of the stress response (neuropeptide Y, epinephrine, norepinephrine, cortisol, and adrenocorticotropic hormone) were evaluated preoperatively and for 72 h after surgery. RESULTS: Perioperative beta-blockade did not significantly alter the hormonal stress response. However, the beta-blocked patients showed improved hemodynamic stability during emergence and postoperatively. They also received less fentanyl intraoperatively (27.7%, P < 0.0001), experienced faster early recovery, had lower pain scores, and required less analgesia in the postanesthesia care unit. Cardiac troponin I release was detected in 8 of 19, 4 of 20, and 5 of 20 patients in groups I, II, and III, respectively (not significant). Three patients in group I had cardiac troponin I levels consistent with myocardial infarction. CONCLUSION: Beta-blockade does not reduce the neuroendocrine stress response, suggesting that this mechanism is not responsible for the previously reported improved cardiovascular outcome. However, it confers several advantages, including decreased analgesic requirements, faster recovery from anesthesia, and improved hemodynamic stability. The release of cardiac troponin I suggests the occurrence of perioperative myocardial damage in this elderly population, which appears to be independent of the neuroendocrine stress response.

Adrenergic beta-Antagonists↗
PubMed1999

Greening under high light or cold temperature affects the level of xanthophyll-cycle pigments, early light-inducible proteins, and light-harvesting polypeptides in wild-type barley and the chlorina f2 mutant

Etiolated seedlings of wild type and the chlorina f2 mutant of barley (Hordeum vulgare) were exposed to greening at either 5 degrees C or 20 degrees C and continuous illumination varying from 50 to 800 &mgr;mol m-2 s-1. Exposure to either moderate temperature and high light or low temperature and moderate light inhibited chlorophyll a and b accumulation in the wild type and in the f2 mutant. Continuous illumination under these greening conditions resulted in transient accumulations of zeaxanthin, concomitant transient decreases in violaxanthin, and fluctuations in the epoxidation state of the xanthophyll pool. Photoinhibition-induced xanthophyll-cycle activity was detectable after only 3 h of greening at 20 degrees C and 250 &mgr;mol m-2 s-1. Immunoblot analyses of the accumulation of the 14-kD early light-inducible protein but not the major (Lhcb2) or minor (Lhcb5) light-harvesting polypeptides demonstrated transient kinetics similar to those observed for zeaxanthin accumulation during greening at either 5 degrees C or 20 degrees C for both the wild type and the f2 mutant. Furthermore, greening of the f2 mutant at either 5 degrees C or 20 degrees C indicated that Lhcb2 is not essential for the regulation of the xanthophyll cycle in barley. These results are consistent with the thesis that early light-inducible proteins may bind zeaxanthin as well as other xanthophylls and dissipate excess light energy to protect the developing photosynthetic apparatus from excess excitation. We discuss the role of energy balance and photosystem II excitation pressure in the regulation of the xanthophyll cycle during chloroplast biogenesis in wild-type barley and the f2 mutant.

Journal Article↗
PubMed1999

Feasibility of routine transradial coronary angiography: a single operator's experience.

The aims of this study were to assess the feasibility of routine transradial coronary angiography in a standard population of patients with presumed coronary artery disease over a period of time long enough to allow for technical evolution and evaluation of a single operator's learning curve, and to provide data for a randomized comparison versus the femoral approach. Between June 1994 and March 1997, transradial angiography was attempted in 1,000 patients. Approximately 25% of these patients were excluded because of an abnormal Allen test. Except in the case of acute myocardial infarction, there was no selection based on symptoms, age, sex, weight or size in the absence of double internal mammary artery bypass graft operation or simultaneous right heart catheterization. Symptoms and angiographic results were typical of a standard population. The right radial approach was used in 95% of the cases for ease of handling and comfort of a right-handed operator. Radial artery puncture and catheterization success was obtained in 97.6% of the cases; the left coronary artery was selectively catheterized in 100%, right coronary artery in 98%, left ventricle in 96.9%, mammary artery grafts in 100% and saphenous grafts in 97.2%. Average procedure duration was 18 +/- 9 minutes, and decreased progressively with experience and catheter strategies. The optimal catheter selection would seem to be a single catheter, either left Amplatz or Champ, for both coronary arteries. Two coronary complications and 3 transient neurological complications occurred, but no clinically significant vascular complications requiring surgery or transfusion were reported. Transradial angiography seems to be a routine approach that should now be compared with the femoral approach and supersede the brachial approach whenever possible.

Aged↗
PubMed1998

ClpB in a cyanobacterium: predicted structure, phylogenetic relationships, and regulation by light and temperature.

The sequence of a genomic clone encoding a 100-kDa stress protein of Plectonema boryanum (p-ClpB) was determined. The predicted polypeptide contains two putative ATPase regions located within two highly conserved domains (N1 and N2), a spacer region that likely forms a coiled-coil domain, and a highly conserved consensus CK2 phosphorylation domain. The coiled-coil region and the putative site of phosphorylation are not unique to p-ClpB; they are present in all ClpB sequences examined and are absent from the ClpB paralogs ClpA, ClpC, ClpX, and ClpY. Small quantities of a 4.5-kb p-clpB transcript and 110-kDa cytosolic p-ClpB protein were detected in cells grown under optimal conditions; however, increases in the quantities of the transcript and protein were observed in cells grown under excess light and low temperature conditions. Finally, we analyzed ClpA, ClpB, and ClpC sequences from 27 organisms in order to predict phylogenetic relationships among the homologs. We have used this information, along with an identity alignment, to redefine the Clp subfamilies.

Amino Acid Sequence↗
PubMed1998

Expert systems in anesthesiology.

There are only a limited number of computer-based systems designed to support anesthesiologists in the operating room. This is evident from the very small number of publications on this topic. These systems may be classified by the functions they perform and include: intelligent anesthesia workstations (with current data acquisition, conditioning and analysis subsystems), systems to detect critical conditions in patients (including expert systems in smart alarm capacity), anesthesia management systems (for planning and management) and drug administration systems. Drug administration systems may be subdivided into open-loop and closed-loop systems. The techniques applied for design of such systems vary extensively. There are traditional rule-based expert systems and probability-based systems, and more recently developed artificial intelligence methods, such as neural networks and fuzzy logic. Computers are valuable tools that have the potential to assist anesthesiologists in carrying out cumbersome and monotonous processes. Future efforts may result in the development of sophisticated systems capable of assuming more responsibilities and of reducing human workload and stress.

Journal Article↗
PubMed1997

Polymorphonuclear leukocytes from asthmatics release more calcium from intracellular stores and have enhanced calcium increase after stimulation with N-formyl-methionyl-leucyl-phenylalanine.

Polymorphonuclear leukocytes isolated from peripheral blood of asthmatics appear to be primed to release more reactive oxygen species than cells of healthy subjects. The enhanced agonist-induced rise in the intracellular free calcium concentration may be responsible for this increased respiratory burst. To test this hypothesis we studied the N-formyl-methionyl-leucyl-phenylalanine- and cyclopiazonic acid--(an inhibitor of Ca(2+)-ATPase of intracellular calcium stores) induced calcium increase in the polymorphonuclear leukocytes of 28 subjects (16 with moderate asthma, 69.6% +/- 8.3% predicted normal peak expiratory flow and 12 normal controls) using a fluorescent probe Fura-2AM at 100 nM and 1 mM extracellular calcium concentrations. In 1 mN calcium, the N-formyl-methionyl-leucyl-phenylalanine-induced calcium increase was 1.7-fold higher in asthmatics than in healthy subjects. Similarly, the contribution of calcium from intracellular stores to the calcium response to N-formyl-methionyl-leucyl-phenylalanine was higher in asthmatics (55% +/- 14% vs. 39% +/- 14%, P < 0.01). The pool of calcium released from intracellular stores by N-formyl-methinoyl-leucyl-phenylalanine and cyclopiazonic acid was 2.3- and 2.2-fold larger than in control cells. There was a correlation between maximal intracellular calcium concentration related to N-formyl-methionyl-leucyl-phenylalanine-induced calcium release from intracellular stores and forced expiratory volume in 1 s expressed as percentage predicted and reversibility in asthmatics (r = 0.63, r = -0.53, P < 0.05). In conclusion, polymorphonuclear leukocytes of asthmatics exhibit an altered calcium response that is mainly dependent on increased calcium release from intracellular stores.

Adult↗
PubMed1997

Altered intracellular calcium signalling after PAF stimulations in polymorphonuclear leukocytes from asthmatic patients.

Platelet activating factor (PAF), a potent lipid mediator, has been implicated in the pathogenesis of airways inflammation in bronchial asthma. Binding of PAF to its receptor (Nakamura et al., 1991) leads to changes of intracellular Ca2+ concentration ([Ca2+]i) that is crucial to cell activation. Therefore, the aim of our study was to investigate whether PMNL of asthmatic patients stimulated with PAF (10(-7) M) differ in relation to changes of [Ca2+]i from cells of healthy subjects. PMNL from asthmatic patients revealed attenuated first response to PAF stimulation--increase in [Ca2+]i (delta[Ca2+]i) was 1.3-fold lower in cells of asthmatics (P < 0.05) versus PMNL of healthy subjects. As determined in experiments with low extracellular calcium concentration, Ca2+ release from internal stores tended to be increased in asthmatics and hence the difference in total Ca2+ response was related to decrease in Ca2+ influx. Thus the contribution of Ca2+ from internal stores to the total first Ca2+ response upon PAF stimulation was two-fold higher (58 +/- 18 vs. 29 +/- 8%, P < 0.001) in PMNL of asthmatics compared with healthy subjects. Two subsequent Ca2+ responses evoked by stimulations with the agonist in 1 mM Ca2+ buffer did not differ between study groups. In low Ca2+ buffer PMNL of 50% of asthmatics responded to the second stimulation while cells of healthy subjects remained unresponsive. The altered Ca2+ responses in PMNL of asthmatic subjects may reflect previous contact with mediator(s) that occur in vivo which may be at least partially explained by the phenomenon of down regulation reported for PAF receptor upon cell stimulation.

Adult↗
PubMed1997

Staphylococcal serine proteinase increases intracellular free calcium concentration in human polymorphonuclear leukocytes.

Staphylococcal serine proteinase (SSP) can influence various functions of human polymorphonuclear leukocytes (PMNL) including chemotaxis and phagocytosis. Since the rise in intracellular free calcium concentration is an important step in signal transduction leading to phagocyte activation, we tested the ability of SSP to increase the intracellular free calcium concentration in human PMNL using the fluorescent calcium indicator Fura-2AM. PMNL isolated from healthy donors responded to SSP in the concentration range of 10 to 100 micrograms/ml. The highest Ca2+ rise (104 +/- 47 nM) was observed for 10 micrograms/ml SSP. It was mainly dependent (81 +/- 11%) on extracellular calcium influx, however, SSP mobilized 68 +/- 7% of Ca2+ from intracellular calcium stores. Boiling of SSP or preincubation with phenylmethylsulphonylfluoride (an serine proteinase inhibitor) did not change its ability to increase intracellular free calcium concentration in PMNL. It suggests that active center of SSP is not responsible for Ca2+ mobilization. Finally, PMNL responded to each of three consecutive stimulations with SSP independently of the presence of high or low extracellular Ca2+ concentration. This may be an additional mechanism responsible for activation of human PMNL and degradation of alveolar walls during the staphylococcal infection in the lower airways.

Adult↗
PubMed1997

An algorithm for assessing intraoperative mean arterial pressure lability.

BACKGROUND: Intraoperative blood pressure lability may be related to risk factors, hypovolemia, light anesthesia, and morbid outcomes, but the measurements of lability in previous studies have been limited by imprecise and infrequent data collection methods. Computerized intraoperative data acquisition systems have provided an opportunity to readdress the issue of intraoperative blood pressure lability with more abundant and precise data. This study sought to derive and validate an algorithm (expert system) to measure mean arterial pressure (MAP) lability. METHODS: Two hundred thirty-nine computerized anesthesis records were reviewed retrospectively. Three anesthesiologists separately rated MAP as very stable, average, or very labile. The parameters of a computer algorithm that measured the change of median MAP between consecutive 2-min epochs were optimized to achieve the best possible agreement among the anesthesiologists. The algorithm was then validated on 229 additional anesthesia records. RESULTS: The proportion of consecutive 2-min epochs in which the absolute value of the fractional change of median MAP exceeded 0.06 (i.e., 6%) correlated strongly with the anesthesiologists' ratings (r = 0.78; P < 0.0001). The optimal sensitivity and specificity of the algorithm for detecting MAP lability were 98% and 59%, respectively. CONCLUSIONS: One potential application of expert systems to anesthesia practice is a "smart alarm" to detect blood pressure lability. It may also provide a better tool to assess the relation between lability and outcome than has been available previously.

Algorithms↗