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PubMed1995

27Al magic-angle spinning nuclear magnetic resonance satellite transition spectroscopy of glasses in the system K2O-Al2O3-SiO2.

27Al magic-angle spinning nuclear magnetic resonance satellite transition spectroscopy at 78 MHz has been applied to determine (true) chemical shift and quadrupole coupling parameters of glasses in the system K2O-Al2O3-SiO2 with 60-80 mol% SiO2 and K2O concentrations between 0 and 24 mol%. The powdered crystalline aluminosilicates andalusite and sillimanite have also been examined. In the glasses, all Al appears to be tetrahedrally bound in the aluminosilicate network unless x = mol% K2O:mol% Al2O3 becomes extremely small. Upon decreasing x the distortion of the tetrahedral Al(OSi)4 units increases in steps, and possible explanations are discussed. Six-coordinated aluminum observed for x < 0.2 is connected with the occurrence of interstitial Al3+ ions which charge-compensate the AlO4 units in addition to K+.

Aluminum↗
PubMed1994

Studies on the contracture inducing action of triphenyltin in the mouse diaphragm.

Triphenyltin induces a contracture of the mouse phrenic nerve-diaphragm preparation. This contracture was not inhibited by (+)-tubocurarine, high magnesium or the absence of electrical stimulation. Triphenyltin (0.1 mM) reduced the muscle membrane potential, the amplitude of the muscle action potential and the muscle membrane input resistance. Pretreatment with high K+ (25 mM) or veratridine (1.5 microM; a Na+ channel activator) briefly shortened the onset of the contracture and increased the peak tension of the contracture. Pretreatment with tetrodotoxin (0.3 microM; a Na+ channel blocker) or glycerol (a T tubule uncoupler) however, significantly reduced the triphenyltin-induced contracture. Removing Ca2+ from external solution and prolonged treatment with either caffeine (20 mM) or ryanodine (2 microM) inhibited the triphenyltin-induced contracture. However, a brief treatment with a lower concentration of caffeine (10 mM) potentiated the contracture. 45Ca2+ uptake studies showed that triphenyltin caused the muscle to accumulate Ca2+ which entered from external solution. Pretreatment with trypsin and dithiothreitol (a sulfhydryl-containing reducing agent) blocked the contracture induced by triphenyltin. These results suggest that triphenyltin initially interacts with the sulfhydryl groups of membrane bound proteins (possibly the Na+ channel) to cause depolarization of the muscle fibres. This depolarization triggers the release of Ca2+ from sarcoplasmic reticulum through the mechanism of Ca2+ inducing Ca2+ release, activates the contractile filaments and causes the muscle to contract.

Action Potentials↗
PubMed1988

A comparison of blood, crystalloid and oxygenated crystalloid cardioplegia solutions on myoglobin and creatine kinase release following cardiac surgery.

Oxygenated crystalloid cardioplegia was found not to produce better cardioprotection than blood or crystalloid cardioplegia, as assessed by myoglobin and creatine kinase MB (CPK-MB) isoenzyme, in patients undergoing coronary artery surgery. Myoglobin and CPK-MB levels were found to peak at 1 and 3 h, respectively, following release of the aortic cross-clamp. There was a good correlation between peak myoglobin and CPK-MB levels. CPK-MB of non-cardiac origin was found to represent a substantial proportion of total CPK-MB 4 h after the release of the aortic cross-clamp.

Blood↗
PubMed1993

Comparison of cardioprotection with crystalloid and blood cardioplegia in CABG patients.

One hundred patients scheduled for elective coronary artery bypass grafting (CABG) were randomly allocated to two groups for myocardial preservation:blood cardioplegia (BCP) or crystalloid cardioplegia (CCP). The study protocol comprised recording of the following parameters: mode of resumption of cardiac rhythm, CK-MB analysis, ECG recording, cardiac output measurement, cross-clamping and perfusion times, and clinical outcome. The study period covered the time from commencement of anesthesia to the first postoperative morning. Spontaneous resumption of sinus rhythm was recorded only in the BCP group (22/51 v 0/49, P < 0.001). CK-MB values were similar in both groups, but 1 hour postoperatively the BCP group had lower values (58.8 +/- 26.7 v 74.5 +/- 31.5 U/L, P = 0.0098 by t test). Fifteen patients in the BCP group did not receive any electric countershock; this subgroup had very low CK-MB values. There were four intraoperative myocardial infarctions in the BCP group and two in the CCP group (BCP: 3/51 v CCP: 3/49, P = 0.68). The results suggest better cardioprotection with blood cardioplegia in this subgroup of patients. Spontaneous resumption of normal cardiac rhythm seems to indicate good myocardial preservation, as reflected in markedly lower CK-MB values in this subgroup.

Blood↗
PubMed1993

Relaxation responses of the coronary microcirculation after cardiopulmonary bypass and ischemic arrest with cardioplegia: implications for the treatment of postoperative coronary spasm.

Coronary arteriolar spasm may occur following cardiopulmonary bypass and ischemic arrest, resulting in impaired cardiac function. Because myocardial perfusion is principally regulated by the microcirculation, the in vitro effects of various clinically used vasodilating drugs on porcine coronary microvessels less than 200 microns in diameter were examined following cardioplegic arrest and reperfusion. After 1 hour of ischemic arrest using either crystalloid or blood cardioplegia solutions followed by 1 hour of reperfusion, microvessels were studied in a pressurized (40 mmHg), no-flow state, and imaged with a video tracking device. Vessels were preconstricted by 30% to 60% of their resting diameter using acetylcholine, and various vasodilatory agents were applied extraluminally. Responses to the beta-adrenergic receptor agonist isoproterenol and the nitrovasodilator sodium nitroprusside were minimally altered by either cardioplegia solution as compared to control. In contrast, relaxation responses to both the calcium channel antagonist nifedipine and nitroglycerin were diminished after ischemic arrest and reperfusion. Relaxation responses were similar with crystalloid or blood cardioplegia for all drugs tested. Despite its somewhat attenuated response, nifedipine remained the most potent vasodilator of those studied. It is concluded that (1) following ischemic arrest with either crystalloid or blood cardioplegia solutions, responses to sodium nitroprusside and isoproterenol were minimally altered, while responses to nifedipine and nitroglycerin were attenuated; (2) relaxation responses of coronary arterioles were not significantly different with either blood or crystalloid cardioplegia; and (3) despite a slightly decreased response after cardioplegia, nifedipine was the most potent vasodilator of coronary arterioles, and may be the best choice for treating postoperative coronary arteriolar spasm.

Animals↗
PubMed1994

Comparison between vaginal swab and endocervical swab during pelvic examination.

PURPOSE: While wet mounts and potassium hydroxide (KOH) preparations are frequently used to help diagnose vaginitis and cervicitis, the sample site varies. This study was conducted to evaluate whether the specimen site (vaginal pool versus endocervical specimen) affects diagnostic sensitivity. METHODS: The study involved 116 consecutive adolescent females presenting to a medical clinic serving high-risk youth. During the pelvic examination, specimens were obtained from the endocervix and the vagina (posterior fornix and sidewall) and placed in separate tubes of normal saline. Each specimen was examined for trichomonads, white blood cells, pseudohyphae, clue cells, and amine odor using 10% potassium hydroxide. RESULTS: The sensitivity was highest for the vaginal specimen in detecting the presence of trichomonads (100% versus 50%), pseudohyphae (76% versus 65%), and clue cells (95% versus 50%). For those with symptomatic candida vaginitis (n = 12), there was no difference in sensitivity (83%) between the two methods for detecting pseudohyphae. Nineteen of the adolescents had a diagnosis of cervicitis (chlamydia by DFA, gonorrhea by culture, and trichomonas by wet mount). If > 5 white blood cells/high powered field (WBC/HPF) was used as a criterion for the presence of a cervicitis, the vaginal sample had a sensitivity of 79% (15/19) and a specificity of 67%, while the endocervical sample had a 74% sensitivity (14/19) and a 57% specificity. CONCLUSIONS: A wet mount obtained from either the vaginal pool or endocervix is not highly specific for diagnosing a vaginitis or cervicitis. However, obtaining a specimen for wet mount and KOH swab from the vaginal pool is more sensitive for detecting trichomonads, pseudohyphae, or clue cells than an endocervical swab.

Adolescent↗
PubMed1995

Effect of density-gradients on the binding of photosensitizing agents to plasma proteins.

The binding of photosensitizing agents to low-density lipoprotein is considered an important factor in tumor localization. We examined the affinity of a group of photosensitizers, varying in charge and hydrophobicity, for LDL, under conditions designed to determine whether the high salt concentration involved in conventional KBr gradients affected the results. Density-gradients containing KBr vs D2O were evaluated; the latter can delineate VLDL and LDL from other plasma components, while the KBr gradient readily resolved VLDL, LDL, HDL and albumin. Distribution of the photosensitizers to plasma fractions was assessed, along with the effect of Cremophor EL, an emulsifier used for formulation of water-insoluble drugs. Both the D2O and KBr gradients provided similar results with regard to the affinity of anionic, neutral or cationic photosensitizers for LDL. The use of Cremophor EL for drug formulation was associated with an altered electrophoretic lipoprotein profile. In some cases, affinity of CRM-solubilized sensitizers for plasma components varied with the density-gradient employed. The high salt concentration used in density-gradient fractionation had little effect on the affinity of photosensitizing agents to low-density lipoprotein but may introduce artifacts when emulsifiers are used in drug formulation.

Blood Proteins↗
PubMed2005

Analysis of thyroid gland microvascularization in rats induced by ingestion of potassium bromide: a scanning electron microscopy study.

The microvascularization of the thyroid gland in rats was studied in animals following ingestion of potassium bromide in various concentrations in drinking water (15, 50 or 100 mg/l) over a period of either 16 or 66 days. Accordingly, animals were divided into six study groups and one control group. Microvascularization was compared among the groups. The pattern of thyroidal follicle distribution within the blood vessels was evaluated by scanning electron microscopy. Animals that ingested potassium bromide presented an increased density and number of meshes in the capillary network of the follicle. The peripheral vessels showed flattening of the walls and in the central portion of the follicle, the distribution of the capillary network did not undergo any morphologic alteration.

Administration, Oral↗
PubMed2005

High-sensitive determination of coenzyme Q(10) in iodinate-beta-cyclodextrin medium by inclusion reaction and catalytic polarography.

A novel polarographic method for the determination of coenzyme Q(10) in beta-cyclodextrin (beta-CD) and iodinate system is proposed. The stability of coenzyme Q(10) to light was improved by the formation of coenzyme Q(10)-beta-CD inclusion complex. In addition, the sensitivity for the determination of coenzyme Q(10) was enhanced by both the formation and the polarographic catalytic wave of the inclusion complex in the presence of iodinate. In 0.1 mol/L HAc-NaAc (pH 4.7)-5.0 x 10(-5) mol/L beta-CD-1.2 x 10(-3) mol/L potassium iodinate-ethanol/water (60:40, v/v) medium, coenzyme Q(10)-beta-CD inclusion complex yielded a sensitive association/parallel catalytic wave. The second-order derivative peak current of the catalytic wave was proportional to coenzyme Q(10) concentration in the range of 6.0 x 10(-8)-2.5 x 10(-7) mol/L, and the detection limit was 1.0 x 10(-8) mol/L. The proposed method has high analytical sensitivity and is allowed to determine coenzyme Q(10) under light.

Catalysis↗
PubMed2006

Effect of soil humic and fulvic acids, pH and ionic strength on Th(IV) sorption to TiO2 nanoparticles.

Thorium is considered as a chemical analog of other tetravalent actinides. Herein, the sorption of Th(IV) on TiO(2) in the presence or absence of soil fulvic acid (FA)/humic acid (HA) as a function of pH, ionic strength and FA/HA concentration has been studied by a batch method. The morphology was characterized by scanning electron microscopy (SEM). The results indicate that sorption of Th(IV) on TiO(2) increases from 0% to approximately 94% at pH 1 approximately 4, and then maintains level with increasing pH values. Both FA and HA have a positive effect on Th(IV) sorption at low pH values and the contribution of FA on Th(IV) sorption is rather higher than that of HA at pH<4. The sorption is weakly dependent on the concentration of KNO(3) in solution, but the cations K(+), Na(+) and Li(+) influence Th(IV) sorption more obviously. The batch results indicate that the inner sphere complex formation is formed at bare surfaces or FA/HA-bound TiO(2) particle surfaces. Results of SEM analysis show that the particle sizes of TiO(2), Th-TiO(2) and Th-HA-TiO(2) colloids are quite different. Surface complexation may be considered as the main sorption mechanism.

Adsorption↗
PubMed2006

Retention of KOH-soluble fluoride on enamel and dentine under erosive conditions--A comparison of in vitro and in situ results.

OBJECTIVES: Aim of the study was to investigate the stability of CaF(2)-like precipitates on enamel and dentine under neutral or acidic conditions and to compare in vitro and in situ results. METHODS: Human enamel and dentine specimens were fluoridated (Elmex fluid, 5 min) and subjected to erosive demineralisation (Sprite light: 3/day each; 30 s in vitro, 2 min in situ) or stored under neutral conditions for 4 (in vitro) or 7 (in situ) days. KOH-soluble fluoride was determined using an ion selective electrode. Between the acid attacks, specimens were stored in remineralisation solution (in vitro) or retained in the oral cavity (four volunteers for enamel and dentine each). RESULTS: Initially, high amounts of KOH-soluble fluoride were gained (between 77.9+/-12.3 and 96.0+/-46.4 microg/cm2). Under neutral conditions in vitro, a significant decrease on enamel (16.2+/-5.0 microg/cm2) and dentine (18.6+/-10.5 microg/cm2) was found, which was more severe under acidic conditions (6.3+/-3.0 and 5.1+/-2.1 microg/cm2, respectively). Under in situ conditions, KOH-soluble fluoride was strikingly stable on enamel under neutral (42.3+/-12.6 microg/cm2) as well as under acidic conditions (54.1+/-17.4 microg/cm2). On dentine, the dissolution kinetics of KOH-soluble fluoride was similar to the in vitro conditions, but the loss was less severe (45.3+/-12.9 microg/cm2 under neutral and 8.8+/-6.4 microg/cm2 under acidic conditions). CONCLUSIONS: In vitro, more KOH-soluble fluoride was lost under erosive compared to neutral conditions. The intra-oral environment was considerably protective for CaF2-like precipitates especially on enamel.

Amines↗
PubMed2004

Improved profile of bad phosphorylation and caspase 3 activation after blood versus crystalloid cardioplegia.

BACKGROUND: Expression of Bcl-2 family proteins and activation of terminal caspase 3 are important for ischemia-reperfusion-induced apoptosis. Bad and Bax are pro-apoptotic proteins, whereas, phosphorylation of Bad inhibits its binding to and inactivation of anti-apoptotic Bcl-2. Thus, decreases in phospho-Bad would be proapoptotic. We investigated if blood (BCP) or crystalloid cardioplegia (CCP) differentially affects apoptosis gene-related proteins. METHODS: Rabbit hearts were perfused with Krebs-Henseleit buffer (KHB) on a Langendorff apparatus. Control hearts (n = 6) were perfused for 90 minutes without cardioplegic ischemia. In the other two groups, hearts were arrested for 30 minutes (37 degrees C) with BCP (n = 6) or with CCP (n = 6) administered continuously (1.5 mL/min). The hearts were reperfused for 30 minutes with KHB. Left ventricle (LV) performance was measured before cardioplegic arrest and at 30 minutes of reperfusion. In vitro relaxation responses of precontracted microvessels (100-180 microm) were obtained in a pressurized no-flow state. Total and activated or phosphorylated caspase 3, Bcl-2, Bad, and Bax were measured by quantitative immunoblotting using specific antibodies. RESULTS: Blood cardioplegia significantly improved the recovery of LV developed pressure compared to CCP (p < 0.05). The endothelium-dependent relaxation in response to adenosine 5'-diphosphate was greater after BCP than after CCP (59.9 +/- 4% vs 26.9 +/- 6%, respectively; p < 0.05). There were no differences in total protein levels of caspase 3, Bcl-2, Bad, and Bax between the groups. Both BCP and CCP increased caspase 3 activity as compared with controls, but CCP caused more activation of caspase 3 than BCP (6.2 +/- 0.7 fold vs 3.1 +/- 0.4, p < 0.05). Both BCP and CCP induced phosphorylation of Bad at Ser(112), but BCP caused greater phosphorylation of Bad (3.5 +/- 0.2 fold vs 2.0 +/- 0.12 fold, respectively, p < 0.05) than CCP. CONCLUSIONS: Blood cardioplegia is superior to CCP in inhibiting the activation of caspase 3 and in increasing phospho-Bad. These actions of BCP were associated with improved LV function and endothelium-dependent relaxation of coronary microvessels. These results may provide molecular mechanisms by which to improve myocardial protection during cardiac surgery.

Animals↗
PubMed2005

Blood cardioplegia provides superior protection in infant cardiac surgery.

BACKGROUND: We hypothesized that blood cardioplegia preserves myocardial metabolism and function more effectively than St Thomas' crystalloid cardioplegia in infant cardiac surgery. METHODS: Thirty infants with atrioventricular septal defects were randomly allocated to either blood or crystalloid intermittent cold (4 degrees C) cardioplegia. Arterial and coronary sinus blood was analyzed for lactate and oxygen. Cardiac output (thermodilution) and left ventricular function (echocardiography) were evaluated. RESULTS: The lactate concentration in coronary sinus blood early after bypass was significantly higher after crystalloid cardioplegia than after blood cardioplegia (2.1 +/- 0.3 vs 1.3 +/- 0.1 mmol/L, p = 0.006), with a significant myocardial release of lactate after crystalloid but not after blood cardioplegia. Oxygen extraction (arterial-coronary sinus O2 content) was higher early after crystalloid cardioplegia (3.02 +/- 0.13 vs 2.35 +/- 0.22 mmol/L, p = 0.01), possibly reflecting a difference in oxygen debt. The cardiac index was higher after blood cardioplegia (4.9 +/- 0.3 vs 4.0 +/- 0.3 L/min(-1)/m(-2), p = 0.04) and echocardiographic grading of left ventricular function was better (4.1 +/- 0.17 vs 3.5 +/- 0.22 arbitrary units, p = 0.046). CONCLUSIONS: This study indicates that blood cardioplegia preserves myocardial metabolism and function more effectively than crystalloid cardioplegia in infant cardiac surgery. The clinical significance of this finding is uncertain, but the more than 20% increase in cardiac index in the critical phase during weaning from bypass may be advantageous.

Biomarkers↗
PubMed2006

Myocardial metabolism is better preserved after blood cardioplegia in infants.

BACKGROUND: We have previously reported improved hemodynamic function after blood cardioplegia in comparison with crystalloid cardioplegia. Furthermore, lactate was released from the heart after crystalloid cardioplegia but not after blood cardioplegia. The purpose of this study was to determine whether the difference in substrate metabolism between the two cardioplegia methods was restricted to lactate, or whether the difference in metabolic derangement was more extensive. METHODS: Thirty consecutive infants with complete atrioventricular septal defects were included in this prospective, randomized, controlled study. Arterial and coronary sinus blood concentrations of substrates and amino acids were measured after weaning from bypass. RESULTS: After crystalloid cardioplegia, there was a myocardial uptake of glutamate (p = 0.003), leucine (p = 0.03), lysine (p = 0.003), and beta-hydroxybutyrate (p = 0.004), whereas lactate was released (p = 0.03). After blood cardioplegia, there was a myocardial uptake of free fatty acids (p = 0.01) but no uptake of amino acids and no release of lactate. CONCLUSIONS: There are differences in myocardial substrate metabolism between blood cardioplegia and crystalloid cardioplegia, which involve carbohydrates and amino acids. The differences may include lipids but our data in this respect are not conclusive.

3-Hydroxybutyric Acid↗
PubMed2004

Counteracting effects of NADPH oxidase and the Na+/Ca2+ exchanger on membrane repolarisation and store-operated uptake of Ca2+ by chemoattractant-activated human neutrophils.

This study was designed to investigate the possible involvement of NADPH oxidase and the Na(+)/Ca(2+) exchanger in regulating membrane repolarisation and store-operated uptake of Ca(2+) by FMLP (1 microM)-activated human neutrophils. Diphenyleneiodonium chloride (DPI, 5-10 microM) and KB-R7943 (2.5-10 microM), inhibitors of NADPH oxidase and the reverse mode of the Na(+)/Ca(2+) exchanger respectively, were used as pharmacological probes. Transmembrane fluxes of Ca(2+), K(+) and Na(+) were determined radiometrically, while alterations in membrane potential and cytosolic Ca(2+) were evaluated using spectrofluorimetric procedures. DPI, added to the cells at the time of maximum FMLP-activated membrane depolarisation, accelerated the rates of both membrane repolarisation and influx of Ca(2+), while KB-R7943 effectively antagonised these processes. SKF 96365 (10 microM), an antagonist of store-operated Ca(2+) channels, abolished the influx of Ca(2+) into FMLP-activated neutrophils, but had no effects on membrane repolarisation, suggesting that the Na(+)/Ca(2+) exchanger is primarily involved in mediating membrane repolarisation, thereby facilitating uptake of Ca(2+) via store-operated channels. These observations are compatible with prominent negative and positive regulatory roles for NADPH oxidase and the Na(+)/Ca(2+) exchanger respectively in regulating the rates of membrane repolarisation and store-operated uptake of Ca(2+) by chemoattractant-activated neutrophils.

Calcium↗
PubMed2004

Colonization and maintenance of murine embryonic stem cells on poly(alpha-hydroxy esters).

The aim of this study was to determine the ability of various poly(alpha-hydroxy esters) to support the in vitro propagation of murine embryonic stem (ES) cells in an undifferentiated state. To this end, ES cell colonization, growth and Oct-4 immunoreactivity following a 48 h culture period upon poly((D,L)-lactide), poly((L)-lactide), poly(glycolide) and poly((D,L)-lactide-co-glycolide) (PLGA) were assessed. By the analysis of live and dead cell number indices and Oct-4 immunoreactivity, ES cell colonization rate during a 48 h culture period was found to be significantly greater on PLGA compared to all the other unmodified poly(alpha-hydroxy esters) tested. Surface treatment of all polymers with 0.1m potassium hydroxide revealed a significant increase in ES cell live numbers when compared to all unmodified polymers, thus revealing a correlation between polymer content, hydrophilicity and colonization rate. These data suggest that surface treated poly(alpha-hydroxy esters) may be employed for ES cell scale up procedures and in tissue engineering applications requiring the colonization of scaffolds by ES cells in an undifferentiated state. According to such applications, once the designated scaffold has been colonized, ES cell directed differentiation into the desired and fully differentiated, functional adult tissue may then be effected.

Analysis of Variance↗