Comparison of the Bruker Microflex LT and Zybio EXS2600 MALDI TOF MS systems for the identification of clinical microorganisms

The emergence of Matrix-Assisted Laser Desorption/Ionization Time-Of-Flight Mass Spectrometry (MALDI TOF MS) technology has expanded the capabilities for identifying microorganisms in clinical labs, replacing traditional biochemical testing with a proteomic approach. In the present study, we compared results between the two commercial MALDI TOF MS systems, Bruker Microflex LT Biotyper and Zybio EXS2600 Ex-Accuspec, for the identification of 1979 urinary isolates by direct extraction method. Current study found that both systems identified a high percentage of isolates to at least the genus level - Bruker 95.6 % of isolates, Zybio 92.4 %. In the case of 89.5 % of all analyzed spectra, the identification results were consistent between the used devices. The highest score values and the highest percentage of spectra identified to species were obtained for gram-negative bacteria. The results show that both systems are equally good choices in terms of analytical performance for routine microbiological diagnostic procedures.

Study of sample preparation influence on bacterial lipids profile in matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

Lipids are one of the cell components therefore it is important to be able to accurately assess them. One of the analytical techniques used to study lipid profiles is matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI TOF MS). The present study attempted to select optimal conditions for sample preparation and MALDI MS analysis of bacterial lipidome in both positive and negative ion modes using different extraction protocols-Folch, Matyash, and Bligh & Dyer, solvents used to apply samples, and matrices such as 9-aminoacridine (9-AA), α-cyano-4-hydroxycinnamic acid (CHCA), 2,5-dihydroxybenzoic acid (DHB), 2-mercaptobenzothiazole (MBT), and 2,4,6-trihydroxyacetophenone (THAP). The obtained results allowed concluding that DHB or CHCA matrices are suitable for lipid analysis in the positive mode, and in the negative mode THAP or 9-AA. The most appropriate protocol for extracting lipids from bacterial cells was the Bligh & Dyer method in both ionization modes. The use of the solvent TA30, which was a mixture of acetonitrile and 0.1% trifluoroacetic acid in water, provided on the spectra a significant number of signals from lipids in all groups analyzed, such as fatty acyls, glycerolipids, and glycerophospholipids.

Down's syndrome: increased enzymatic antioxidative defense is accompanied by decreased superoxide anion generation in blood

Whole blood leukocytes of DS patients were found to produce less superoxide radical anion than in healthy controls, especially without stimulation with zymosan. This decreased superoxide generation may contribute to the immune system deficiency reported for DS.

Moderate systemic hypothermia and cold crystalloid cardioplegia influence on myocardial ischemic and revascularisative injury

The number of granulocytes, their ability to generate superoxide anion (O2-) and the activities of Cu, Zn--superoxide dismutase (SOD-1), glutathione peroxidase (GSH-Px), catalase (CAT) as well as malonyldialdehyde (MDA) concentrations in erythrocytes in the blood extracted from the venous sinus and aorta under coronary artery bypass were examined with the use of St. Thomas Hospital cardioplegic solution. Specimens at the peak of ischemia of the right atrium for ultrastructural examination of the endothelial cells of capillary vessels and sarcomers were taken. The blood was obtained during cardiopulmonary bypass (CPB) before the aorta clamping and immediately after aorta declamping (peak of ischaemia) between 1-3 minute and 10-13 minute of reperfusion. Increase of the number of granulocytes both in the coronary sinus and aortal blood at all examined intervals as well as decrease in the number of ones in sinus compared with aortal blood was noted. The ability to produce superoxide anion radical decreased at the peak of ischemia and during reperfusion. The activity of SOD-1 was lower both after the period of ischemia and reperfusion. The increase in aortal blood activity during reperfusion was characteristic of GSH-Px; the activity was higher in the blood sample from the coronary sinus taken during ischemia and initial reperfusion. With the exception of the initial reperfusion the activity of CAT diminished in all observed cases. MDA concentration did not demonstrate any significant changes with the exception of the initial reperfusion in the aortal blood and later towards the end of reperfusion in the blood from the coronary sinus. Ultrastructural studies indicated overhydration of the cells both in the endothelium and the intercellular space. The obtained data demonstrate that the applied cardioplegic solution protects the myocardium from harmful effects of reactive oxygen species produced as a result of ischemia and reperfusion.

Changes in the structure and properties of corpus vitreous and the preservation of enzymatic composition of rabbit antioxidative system under the influence of sulphur hexafluoride gas

PURPOSE

To evaluate clinical, physiochemical and biochemical changes in rabbit vitreous body caused by local injection of sulphur hexafluoride gas.

MATERIAL AND METHODS

The volume of fluid vitreous fraction was measured with Na+, K+, Mg2+, Ca2+ levels and full proteins concentration in both vitreous fractions in 24 New Zealand rabbits at 2, 7 and 14 day after SF6 injection. The activity of superoxide dismutase, catalase and malonyl dialdehyde were used to evaluate the activity of antioxidative enzymatic system. Control group consisting of 6 New Zealand rabbits had no experimental procedures.

RESULTS

In the investigated group, the fluid vitreous fraction volume was increased while gelatous one was diminished from 0.08 ml in control group to 0.32 ml in the study group (on day 14). The level of Na+, K+, Mg2+, Ca2+ in the fluid fraction was unchanged. On day 7, we noticed statistically significant increase in protein concentration in comparison with the control group and the study group on 14 day. The activity of superoxide dismutase and catalase as well as the level of malonyl dialdehyde were increased in the fluid vitreous fraction compared to the gelatous one in the control group. After the SF6 injection we did not observe any changes of superoxide dismutase and catalase activities in the gelatous part of vitreous body while in the fluid one there was statistically significant decrease in the enzymatic activity and the MDA level in the whole observation time.

CONCLUSIONS

The injected sulphur hexafluoride gas caused the damage of the gelatous vitreous fraction with the increase in the fluid one. The oxygen free radicals might trigger these pathological processes.

[Changes in the antioxidant system of the vitreous in rabbits after administration of sulfur hexafluoride]

PURPOSE

To evaluate the enzymatic activity of antioxidant system of rabbit's vitreous after sulfur hexafluoride (SF6) application.

MATERIAL AND METHODS

Activity of CuZn-SOD, catalase and concentration of MDA in fluid and gel fraction of vitreous were determined in 24 rabbits of New Zealand race on the 2nd, 7th and 14th day after SF6 application. Control group consisted of 6 animals which did not undergo any operations.

RESULTS

Dismutase and catalase activity as well as MDA concentration were higher in fluid fraction than in gel fraction in animals of control group. After SF6 application the activity of enzymes and MDA concentration did not change, whereas in fluid fraction all these values were statistically significantly reduced in all time intervals.

CONCLUSIONS

SF6 leads to disintegration of vitreous structure especially just after its application. Damage to hyalocytes causes dysfunction of enzymatic system. Specific fluid fraction structure and insufficient number of substrates for peroxidation processes are the reasons for simultaneous reduction of MDA concentration.

[Changes in the antioxidant system of the aqueous humor, lens and erythrocytes after sulfur hexafluoride application to the vitreous of rabbits]

AIM

To determine the activity of superoxide dismutase, catalase and the concentration of malondialdehyde (MDA) in aqueous humor, lens and red blood cells after application of sulfur hexafluoride (SF6) into vitreous of rabbits.

MATERIAL AND METHODS

0.5 ml of 100% SF6 was injected into the vitreous of 24 rabbits of New Zealand race. The animals were randomly divided into 3 groups (of 8 rabbits each) depending on the observation day: group 1-2nd day of experiment, group 2-7th day and group 3-14th observation day. The control group (gr. 0) consisted of 6 rabbits that did not undergo any operations. Activity of superoxide dismutase, catalase and MDA concentration were determined in aqueous humor, lens and systemic blood erythrocytes.

RESULTS

On the 7th day of observation an increased activity of dismutase and catalase as well as simultaneous increased MDA concentration were observed. In the lens on the 7th day the increased activity of dismutase was significant in relation to the results in the next time interval, whereas MDA concentration was significantly lower in all time intervals of the experiment in comparison with control group. In erythrocytes an increased activity of catalase was noticed on the 2nd and 14th day.

CONCLUSIONS

Increased occurrence of active oxygen species in aqueous humor leads to insufficiency of the antioxidant system and intensification of peroxidation processes, which is reflected by increased MDA concentration. However, in the lens of this experimental model a slight stimulation of antioxidant system by a small number of free radicals is observed, which provokes a reaction of sweeping them away. Efficiency of lens antioxidant system is secured by weakening of peroxidation processes, which is expressed in minimal drop of MDA concentration.

[Oxygen-derived free radicals of granulocytes in the blood of patients with chronic inflammation of the middle ear and palatine tonsils]

The evaluation of oxygen species generation in blood granulocytes of patients with chronic inflammation of middle ear and palatine tonils. There were 38 patients tested (10 with chronic inflammation of palatine tonsil, 18 with chronic inflammation of middle ear and 10 healthy ones). There were statistically significant differences between the superoxide anion generation in patients with chronic inflammation of palatine tonsil and middle ear in comparison with to the healthy ones.

[The generation of oxygen free radicals in blood in patients with hypertrophy of paranasal sinuses and larynx]

The evaluated of oxygen specious generation in blood granulocytes of patients with hypertrophy of paranasal sinuses and larynx. There were 33 patients tested (13 with hypertrophy of paranasal sinuses, 10 with hypertrophy of larynx and 10 healthy). The superoxide anion generation of peripheral blood granulocytes described by the rate of the reduced cytochrome C at rest and after stimulation with opsonized zymosan according to Bellavite were measured. There were statistically significant differences between the superoxide anion generation in patients with hypertrophy of paranasal sinuses and larynx in comparison with the healthy ones.

Nitric oxide release in the peripheral blood during hemodialysis

These studies evaluated the nitric oxide (NO) release in peripheral blood during a four-hour hemodialysis (HD) with single-used cuprophane (CU), polysulfone (PS) and polyacrylonitrile (PAN) membranes in 10 chronic uremic patients. Continuous monitoring of blood NO concentrations was performed with a sterile NO sensor probe inserted vertically into the arterial blood line between the arteriovenous fistula and dialyzer. In the initial period of HD two peaks of blood NO concentrations were observed: the first occurred at the very start of HD and lasted approximately one minute, and the second peaked to a lesser extent at 20 to 26 minutes after the initiation of HD. The extent of NO release was dependent on the type of dialysis membrane used. Areas under curves for blood NO concentrations (in mumol x min) were as follows: CU, 450.8 +/- 163.3; PS, 247.3 +/- 150.6*; PAN, 200.4 +/- 91.0* (*P < 0.05 vs. CU). During the first hour of HD (N = 6) blood NO concentrations were significantly higher at the outlet of CU dialyzer than those found at the inlet. The areas under their curves (in mumol x min) were 169.1 +/- 1.9 and 107.5 +/- 1.6, respectively (P < 0.001). Areas under curves for blood NO concentrations measured for five minutes following a five-minute in vitro incubation of 5 ml heparinized uremic blood samples (N = 10) with dialysis membranes (50 cm2) were as follows (in nmol x min): CU, 2380 +/- 289*; PS, 1293 +/- 45*; PAN, 1117 +/- 37*; control, 502 +/- 56 (*P < 0.05 vs. control). The addition of sodium heparin to uremic blood platelet suspension induced an immediate rise in NO release in a dose-dependent manner, which proved to be a hyperbolic relationship. During HD with CU (N = 6), PS (N = 6) and PAN (N = 6) membranes blood plasma cGMP concentrations significantly increased, particularly at 20 and 60 minutes of the procedure. No significant differences in blood plasma cGMP levels were found between individual dialysis membranes, and no significant correlations were observed between blood plasma cGMP levels and blood NO concentrations. The results indicate that during HD NO is released in the peripheral blood due to blood-membrane and heparin-blood platelet interactions. The extent of intradialytic NO release is dependent on the type of dialysis membrane used (CU > PS approximately PAN).

[Metabolic changes in blood oxygen in the human heart under ischemic and reperfusion conditions]

The number of granulocytes, their capability to generate O2-. and the activity of SOD-1, GSH-Px, Cat as well as MDA concentrations in erythrocytes in the blood extracted from the venous sinus and aorta under coronary artery bypass with use of St. Thomas cardioplegic solution were determined. The blood for examination was obtained before the institution of cardiopulmonary bypass, in the period of the deepest ischaemia (just after declamping of the aorta) and between the 1-3 minute and the 10-13 minute of reperfusion. A rise in the number of granulocytes both in the venous sinus and aortal blood at all examined intervals was noted. Capability to produce superoxide anion radicals decreased at the peak of ischemia and during reperfusion. The activity of SOD-1 was lower both after the period of ischemia and reperfusion. A rise in aortal blood activity during reperfusion was characteristic for GSH-Px; the activity was greater in the blood sampled from the coronary sinus during ischemia and initial reperfusion. With the exception of the initial reperfusion the activity of Cat diminished in all observed cases. We did not observe any significant changes in MDA concentration with the exception of the initial reperfusion in the aortal blood and later during reperfusion in the blood from the coronary sinus. The results demonstrate that the applied cardioplegic solution may protect myocardium from harmful effects of active oxygen froms produced as a results of ischemia and reperfusion.

Effect of morphine and naloxone on oxidative metabolism during experimental renal ischemia and reperfusion

During experimental renal ischemia and reperfusion in rabbits, morphine as well as naloxone significantly inhibited the increased superoxide anion (O2-) generation by resting and opsonized zymosan-stimulated phagocytes in renal venous blood. Morphine with naloxone in combination inhibited O2- generation to a lesser extent than that observed when these drugs were used separately. Morphine and/or naloxone did not significantly affect erythrocyte superoxide dismutase (SOD-1), glutathione peroxidase (GPx) and catalase activities or malonyldialdehyde (MDA) concentrations in venous blood during renal ischemia. During reperfusion there was a tendency to a slight reduction of erythrocyte catalase activity in morphine-treated animals, and to slight diminutions of erythrocyte SOD-1 and GPx activities and erythrocyte MDA concentrations in rabbits treated with naloxone and morphine in combination. These results indicate that opioid receptor agonists and antagonists modify the response of the kidney to acute injury. These effects may have relevance to the pattern of oxidative stress seen in patients with acute ischemic renal failure.

[Influence of percutaneous transluminal coronary angioplasty (PTCA) on superoxide anion generation by whole blood granulocytes in patients with unstable angina pectoris (part I)]

In twenty patients with unstable angina, the effects of percutaneous transluminal coronary angioplasty (PTCA) on superoxide anion generation by neutrophils (PMNs) obtained from ulnar vein (UV) and coronary sinus (CS) were investigated. Blood samples for the investigations were taken from CS just before the procedure, within the first minute after the last balloon inflation and 20 minutes after PTCA; from BV--just before the procedure and 20 minutes following it. The results were compared with those obtained from 12 patients with unstable angina, (in whom coronary angiography was performed, but for various reasons angioplasty was desisted from) and with those obtained from 20 clinically healthy persons. In patients with unstable angina, the significantly increased O2.- generation by PMNs from CS and BV was found at rest as well as following opsonized-zymosan stimulation, compared with healthy persons. Within the first minute after PTCA, the significantly decreased O2.- generation by PMNs from CS was observed, compared with the results before the procedure (rest.--11.29 +/- 0.73 and 10.15 +/- 0.65 nmol/cell/min., p < 0.05; stimulation--27.62 +/- 6.25 and 18.54 +/- 3.37 nmol/cell/min., p < 0.05). Twenty minutes after PTCA O2.- generation by PMNs from CS still decreased (rest--9.23 +/- 1.08 nmol/cell/min., stimulation--15.71 +/- 5.98 nmol/cell/min.). In blood samples taken from BV before and after PTCA, no statistically significant differences in O2.- generation were observed (rest--11.32 +/- 0.79 nmol/cell/min. and 10.77 +/- 1.43 nmol/cell/min.; stimulation--25.96 +/- 6.12 nmol/cell/min. and 21.15 +/- 5.47 nmol/cell/min.).

[Some indices of peripheral blood oxidative metabolism during acetate and bicarbonate hemodialysis in patients with chronic uremia]

Whole blood superoxide anion generation, erythrocyte superoxide dismutase (SOD-1) and catalase activities and erythrocyte and plasma malonyldialdehyde concentrations were evaluated during cuprophane hemodialysis using bicarbonate and acetate dialysate. Superoxide anion generation by resting phagocytes was found to be significantly higher during bicarbonate hemodialysis, while its generation by opsonized zymosan--stimulated phagocytes did not differ between hemodialyses with both kinds of dialysates. Changes in the erythrocytes SOD-1 activities, found in the initial period of hemodialysis, were independent of the kind of dialysate, while erythrocyte catalase activity was higher during acetate hemodialysis in comparison with bicarbonate one. The kind of dialysate did not affect extent of erythrocyte membrane lipid peroxidation, while plasma lipid peroxidation was lower during acetate hemodialysis in comparison with bicarbonate one. In vitro studies with blood cells incubated with acetate or bicarbonate ions in concentrations, which are observed in vivo during hemodialysis, suggest that probably these ions do not directly affect superoxide anions generation, erythrocyte SOD-1 and catalase activities and erythrocyte membrane lipid peroxidation.

[Generation of active oxygen compounds by whole blood granulocytes in patients with chronic renal failure]

In patients with chronic renal failure (crf) on conservative treatment whole blood granulocyte superoxide anion (O2-) generation was significantly decreased. Regular hemodialysis treatment did not induce its significant improvement. As granulocyte O2- generation determines production of other active oxygen compounds, this phenomenon may lead to the impairment of phagocyte bactericidal activity and increased susceptibility to infections in crf. Various methods of determination of active oxygen compounds give incomparable results.