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Biomedical subjects

J Lantos

Publications and source records attributed to J Lantos.

At least 19 recordsLinked to original sources

Effect of cardiopulmonary bypass on cytokine network and myocardial cytokine production.

BACKGROUND: In addition to the well-investigated proinflammatory cytokine expression, there is an ever increasing interest in the field of anti-inflammatory response to cardiopulmonary bypass (CPB). Evidence suggests that myocardium serves as an important source of cytokines during reperfusion and application of CPB. The effect of coronary artery bypass graft (CABG) without CPB on myocardial cytokine production has not as yet been investigated. HYPOTHESIS: Cardiopulmonary bypass can cause long-term disturbance in pro- and anti-inflammatory cytokine balance, which may impede a patient's recovery following surgery. Therefore, the effect of CPB on the balance of the pro-/anti-inflammatory cytokines network and myocardial cytokine outflow was assessed throughout a longer period after surgery. METHODS: Twenty patients were scheduled for CABG with CPB and 10 had off-pump surgery. Blood samples were taken before, during, and over the first week following surgery. Coronary sinus blood samples were collected during surgery. The ratio of pro- and anti-inflammatory cytokines was calculated and the cytokine concentration of peripheral and coronary sinus blood were compared in both groups. RESULTS: Pro-/anti-inflammatory cytokine ratio decreased early after CPB followed by a delayed and marked increase. A more balanced ratio was present following off-pump surgery. Coronary sinus levels of certain cytokines exceeded the concentration of systemic blood in the course of CPB but not during off-pump operation. CONCLUSION: Patients show pro-inflammatory predominant cytokine balance at a later stage after CPB in contrast to those without CPB. The heart produces a remarkable amount of cytokines only in the course of surgery with CPB.

Aged↗

A cost-effective screening method for pesticide residue analysis in fruits, vegetables, and cereal grains.

This paper reports the results of studies performed to investigate the potential of applying thin layer chromatography (TLC) detection in combination with selected extraction and cleanup methods, for providing an alternative cost-effective analytical procedure for screening and confirmation of pesticide residues in plant commodities. The extraction was carried out with ethyl acetate and an on-line extraction method applying an acetone-dichloromethane mixture. The extracts were cleaned up with SX-3 gel, an adsorbent mixture of active carbon, magnesia, and diatomaceous earth, and on silica micro cartridges. The Rf values of 118 pesticides were tested in eleven elution systems with UV, and eight biotest methods and chemical detection reagents. Cabbage, green peas, orange, and tomatoes were selected as representative sample matrices for fruits and vegetables, while maize, rice, and wheat represented cereal grains. As an internal quality control measure, marker compounds were applied on each plate to verify the proper elution and detection conditions. The Rf values varied in the different elution systems. The best separation (widest Rf range) was achieved with silica gel (SG)--ethyl acetate (0.05-0.7), SG--benzene, (0.02-0.7) and reverse phase RP-18 F-254S layer with acetone: methanol: water/30:30:30 (v/v) (0.1-0.8). The relative standard deviation of Rf values (CV(Rf)) within laboratory reproducibility was generally less than 20%, except below 0.2 Rf, where the CVRf rapidly increased with decreasing Rf values. The fungi spore inhibition, chloroplast inhibition, and enzyme inhibition were found most suitable for detection of pesticides primarily for confirming their identity or screening for known substances. Their use for determination of pesticide residues in samples of unknown origin is not recommended.

Chromatography, Thin Layer↗

Application of TLC for confirmation and screening of pesticide residues in fruits, vegetables, and cereal grains: Part 2. Repeatability and reproducibility of Rf and MDQ values.

This paper illustrates the effect of major factors influencing the reproducibility of thin layer chromatography (TLC) separation and detection under largely differing environmental and laboratory conditions. The optimum conditions for reproducibility and detection sensitivity was obtained on 20 x 20 cm layer in the retention factor (Rf) range of 0.2-0.7 by applying the sample in spots of 3-4 mm diameter at 2 cm from the edge of the plate. The reproducibility rapidly decreased below Rf = 0.2. Above Rf = 0.2 the within-laboratory reproducibility of 219 pesticides obtained in ethyl acetate silica gel elution system by several laboratories was typically below 10%. The among-laboratories reproducibility of the average retention factors was generally below 12%. The minimum detectable quantities (MDQ) of 219 pesticide residues were determined with nine detection methods. The MDQ values largely varied depending on the mode of detection. Bioassay methods enabled the detection down to 0.1-10 ng, while 20-100 ng could be achieved with the chemical reagents. Higher MDQ values are also reported in order to assist the identification of compounds potentially present. The between-laboratories reproducibility of MDQ values was typically 1-5 MDQmin.

Chromatography, Thin Layer↗

The effect of different levels of peritoneal CO2 pressure on bleeding time of spleen capsule injury.

AIMS: The authors, in contrast to similar injuries with open surgery, had observed spontaneous hemostasis of relatively large spleen capsule injuries during laparoscopic surgery. METHODS: Standard spleen injuries were carried out in 5 anesthetized mongrel dogs at different CO2 pressures and in open surgery. Bleeding was checked every minute by wiping around the injury but not removing the clot. Bleeding time was measured until no more oozing was detected. At every pressure level 3-3 measurements were done and analyzed. Parenchymal pressure of the spleen and systemic blood pressure were detected with direct catheter implantation. RESULTS: In open surgery the average bleeding time was 15.2 min; at 5, 15, and 25 mmHg CO2 pressures bleeding times were 12.3, 10.6, and 9.8 min, respectively. The parenchymal pressure of the spleen (5-6 mmHg) rose synchronously with peritoneal pressure, but no significant changes in systemic blood pressure were seen. CONCLUSION: Peritoneal CO2 pressure may counterweight the parenchymal pressure of the spleen, thus helping hemostasis. There seems to be an inverse proportion between peritoneal pressure and bleeding time. In case of spleen capsule injury during laparoscopic surgery, chances for spontaneous hemostasis are much better compared to open surgery. Attention must be paid to maintain adequate peritoneal pressure.

Animals↗

Epidemiology and ethics in the neonatal intensive care unit.

There are many ethical dilemmas in the neonatal intensive care unit (NICU), and almost as many solutions as dilemmas. Religion, philosophy, natural law, civil law, criminal law, to name but a few, have each been invoked as a source of authority to resolve the inevitable conflicts arising at the confluence of uncertain outcome, physical pain, and financial expenditure. This article takes a different approach. Here we begin by envisioning what we would most like to know about NICU care that we do not currently know (or at least is not widely known), and then combine "thought experiments" with preliminary "real experiments" to acquire a hypothetical database from which ethics in the NICU can be informed.

Ethics, Medical↗

Methadone dosing, heroin affordability, and the severity of addiction.

OBJECTIVES: This study sought to track changes in US heroin prices from 1988 to 1995 and to determine whether changes in the affordability of heroin were associated with changes in the use of heroin by users seeking methadone treatment, as indexed by methadone dose levels. METHODS: Data on the price of heroin were from the Drug Enforcement Administration; data on methadone doses were from surveys conducted in 1988, 1990, and 1995 of 100 methadone maintenance centers. Multivariable models that controlled for time and city effects were used to ascertain whether clinics in cities where heroin was less expensive had patients receiving higher doses of methadone, which would suggest that these patients had relatively higher physiological levels of opiate addiction owing to increased heroin use. RESULTS: The amount of pure heroin contained in a $100 (US) purchase has increased on average 3-fold between 1988 and 1995. The average dose of methadone in clinics was positively associated with the affordability of local heroin (P < .01). CONCLUSIONS: When heroin prices fall, heroin addicts require more methadone (a heroin substitute) to stabilize their addiction--evidence that they are consuming more heroin.

Health Surveys↗

[Thrombotic thrombocytopenic purpura and systemic lupus erythematous. Three cases presenting simultaneously].

Thrombotic thrombocytopenic purpura (TTP) is a clinical syndrome characterized by microangiopathic hemolytic anemia, thrombocytopenia, fever, neurological symptoms, and renal involvement. The relationship of TTP to systemic lupus erythematosus (SLE) has been recognized in the medical literature since 1939. The differential diagnosis is difficult because both diseases have similar clinical features. The mainstay for recognizing TTP in the context of active SLE is the presence of helmet red cells, marked reticulocytosis, and negative direct Coomb's test. We report three female patients with simultaneous presentation of TTP and SLE. We suggest combined treatment with immunosuppressive therapy and plasma exchange using fresh frozen plasma.

Adult↗

[Surgical trauma induced by laparoscopic cholecystectomy].

The objective demonstration of improved postoperative recovery suggests that surgical injury induced by the laparoscopic approach is less intense than that after open surgery. Forty-two patients diagnosed as having noncomplicated gallstones were studied prospectively. They were operated on by laparoscopy (LC, n = 21) or open surgery (OC, n = 21). Both surgical procedures induced significant changes of investigated parameters (acute-phase response, free radical mediated reactions, neutrophil functions). Comparison of the results of the two cholecystectomy techniques showed that laparoscopic cholecystectomy induced a significantly less intense acute-phase response, a more attenuated oxidative stress characterising by free radical mediated reactions and that is less disruptive to neutrophil function. The results and the data from the literature suggest that surgical injury causing by the laparoscopic cholecystectomy is less intense than that after open cholecystectomy, which can explain partially the better clinical outcome following laparoscopic versus open procedure.

Cholecystectomy↗

A proactive, data-based determination of the standard of medical care in pediatrics.

A 3-week-old infant awoke with a fever. He was taken to the doctor who noted that the child was irritable. The doctor took him to the hospital where a resident performed a spinal tap, started an intravenous (IV) line, and ordered antibiotics. The entire drama, from entering the doctor's office to infusion of ampicillin, took 2 hours. The doctor was sued for malpractice. Expert witnesses for the plaintiff testified that he had deviated from the standard of medical care by taking too long to administer antibiotics, which, in their view, ought to have been given within 30 minutes. Expert witnesses for the defense testified that 2 hours to administer antibiotics in this case was within the standard of care. What ought to be the response of the pediatric community to discrepant expert testimony such as this? One possible response is nothing. Lawyers from both sides will find expert medical witnesses who articulate positions favorable to their clients (as they did in this case), and the truth will emerge after vigorous cross-examination. This, we suggest, is inadequate. We believe that some expert opinions can be viewed as better than others. That is, some opinions describe the standard of medical care correctly while other expert opinions are (to put it charitably) idiosyncratic, failing to depict accurately the skill and care ordinarily administered in comparable situations. Currently, jurors are informed about the standard of care by expert witnesses, who rely on their own medical knowledge and experience. However, a huge body of literature demonstrates that recollections of individual experience are inevitably flawed, and flawed in a nonrandom direction (the Monday morning quarterback phenomenon). Consider the infant with meningitis. When experts in pediatric emergency medicine and pediatric infectious diseases (ID) were asked about the median time from emergency room (ER) presentation to administration of antibiotics in a child with suspected meningitis, their opinions were wrong and slanted toward the outcome known to be desired (namely, a shorter elapsed time). ER physicians (median estimated time to antibiotic administration [AB-TIME] = 46 minutes) and ID physicians (median estimated AB-TIME = 80 minutes) consistently underestimated the actual median value of AB-TIME determined by chart review (120 minutes). From the judicial perspective such potential flaws in expert testimony are assumed to be equally distributed among experts. All admissible evidence is a priori of equal weight until a jury decides otherwise. The standard of medical care is created anew by expert testimony in each individual case, disappearing, like Brigadoon, upon resolution of the dispute. However, to anyone but a lawyer, the standard of medical care must exist as something outside the courtroom testimony of experts, and if it does exist, it should be easily described so that expert testimony can be judged more (or less) accurate in depicting it. We contend that medical care is not a single behavior that conforms to or deviates from an idiosyncratic and retrospectively determined standard, but rather a distribution of behaviors in response to a variety of medical circumstances. For a given scenario, each of several possible responses can be ascribed a relative frequency based on empirical data, and the consequent normal curve depicts the totality of medical care. Substandard care then falls out neatly as behaviors lying outside the large majority of cases. Juries would be empowered (as they are currently) to determine exactly where on this curve substandard care lies, but at least the debate would share the same description of reality. Recent US Supreme Court guidelines regarding expert testimony provide an opportunity to expand the use of databases in medical negligence cases. The Court restricted expert testimony to "scientific knowledge ... based on generating hypotheses and testing them to see if they can be falsified ... (ABSTRACT TRUNCATED)

Databases as Topic↗