CHARMM general force field: A force field for drug-like molecules compatible with the CHARMM all-atom additive biological force fields

The widely used CHARMM additive all-atom force field includes parameters for proteins, nucleic acids, lipids, and carbohydrates. In the present article, an extension of the CHARMM force field to drug-like molecules is presented. The resulting CHARMM General Force Field (CGenFF) covers a wide range of chemical groups present in biomolecules and drug-like molecules, including a large number of heterocyclic scaffolds. The parametrization philosophy behind the force field focuses on quality at the expense of transferability, with the implementation concentrating on an extensible force field. Statistics related to the quality of the parametrization with a focus on experimental validation are presented. Additionally, the parametrization procedure, described fully in the present article in the context of the model systems, pyrrolidine, and 3-phenoxymethylpyrrolidine will allow users to readily extend the force field to chemical groups that are not explicitly covered in the force field as well as add functional groups to and link together molecules already available in the force field. CGenFF thus makes it possible to perform "all-CHARMM" simulations on drug-target interactions thereby extending the utility of CHARMM force fields to medicinally relevant systems.

Montelukast, a leukotriene-receptor antagonist, for the treatment of mild asthma and exercise-induced bronchoconstriction

BACKGROUND

Patients with mild asthma frequently have only exercise-induced bronchoconstriction, a symptom of inadequate control of asthma. We evaluated the ability of montelukast, a leukotriene-receptor antagonist, to protect such patients against exercise-induced bronchoconstriction.

METHODS

We randomly assigned 110 patients (age, 15 to 45 years) with mild asthma and a decrease in the forced expiratory volume in one second (FEV1) of at least 20 percent after exercise on two occasions during a placebo run-in period to receive 10 mg of montelukast (54 patients) or placebo (56 patients) once daily at bedtime for 12 weeks in a double-blind study. Treatment was followed by a two-week, single-blind washout period during which all patients received placebo. Exercise challenges were performed at base line; 20 to 24 hours after dosing at weeks 4, 8, and 12; and at the end of the washout period. The primary end point was the area under the curve for FEV1 (expressed as the percent change from base-line values) in the first 60 minutes after exercise. This measure summarized the extent and duration of bronchoconstriction after exercise.

RESULTS

At 12 weeks, montelukast therapy offered significantly greater protection against exercise-induced bronchoconstriction than placebo therapy (expressed as the percentage of inhibition of the end points), as evidenced by the improvement in the area under the FEV1 curve (degree of inhibition, 47.4 percent; P=0.002). Montelukast therapy was also associated with a significant improvement in the maximal decrease in FEV1 after exercise (P=0.003) and the time from the maximal decrease in FEV1 to the return of lung function to within 5 percent of pre-exercise values (P=0.04). The differences between groups in the various measures of lung function were similar at 4, 8, and 12 weeks; there was no evidence of rebound worsening of lung function in the montelukast group after the washout period. After 12 weeks of treatment, patients in the montelukast group were more likely to rate their asthma control as better and less likely to require rescue therapy with a beta-agonist during or after exercise challenge. The rates of adverse events were similar in the two groups.

CONCLUSIONS

As compared with placebo, once-daily treatment with montelukast provided significant protection against exercise-induced asthma over a 12-week period. Tolerance to the medication and rebound worsening of lung function after discontinuation of treatment were not seen.

Significance of prenatal, perinatal and postnatal factors in the development of AGA preterm infants at five to seven years

The effects of prenatal, perinatal and postnatal events on developmental outcome at five to seven years of preterm infants with birthweights appropriate for gestational age were investigated in two separate cohorts: one a longitudinal study of 97 infants, the other a cross-sectional study of 249 infants. Among the prenatal variables, the number of minor congenital anomalies was negatively correlated with neurological development, as was the deformation score. The pregnancy optimality score was not significantly related to outcome. Among the perinatal variables, gestational age and birthweight had some significant correlations with development, but birth and neonatal optimality scores were only inconsistently significant in relation to outcome. Socio-economic status was strongly related to language and intellectual development. Infants with gestations of 32 to 36 weeks had a more favourable neurological and intellectual outcome than those born before 32 weeks: however, the former group comprised about 80 per cent of the population studied, so the majority of children with lower function were found in that group.

Platelet GP IIIa Pl(A) polymorphisms display different sensitivities to agonists

BACKGROUND

Both inherited predisposition and platelet hyperreactivity have been associated with ischemic coronary events, but mechanisms that support genetic differences among platelets from different subjects are generally lacking. Associations between the platelet Pl(A2) polymorphism of GP IIIa and coronary syndromes raise the question as to whether this inherited variation may contribute to platelet hyperreactivity.

METHODS AND RESULTS

In this study, we characterized functional parameters in platelets from healthy donors with the Pl(A) (HPA-1) polymorphism, a Leu (Pl(A1)) to Pro (Pl(A2)) substitution at position 33 of the GP IIIa subunit of the platelet GP IIb/IIIa receptor (integrin alpha(IIb)beta(3)). We studied 56 normal donors (20 Pl(A1,A1), 20 Pl(A1,A2), and 16 Pl(A2,A2)). Compared with Pl(A1,A1) platelets, Pl(A2)-positive platelets showed a gene dosage effect for significantly greater surface-expressed P-selectin, GP IIb/IIIa-bound fibrinogen, and activated GP IIb/IIIa in response to low-dose ADP. Surface expression of GP IIb/IIIa was similar in resting platelets of all 3 genotypes but was significantly greater on Pl(A2,A2) platelets after ADP stimulation (P=0.003 versus Pl(A1,A1); P=0.03 versus Pl(A1,A2)). Pl(A1,A2) platelets were more sensitive to inhibition of aggregation by pharmacologically relevant concentrations of aspirin and abciximab.

CONCLUSIONS

Pl(A2)-positive platelets displayed a lower threshold for activation, and platelets heterozygous for Pl(A) alleles showed increased sensitivity to 2 antiplatelet drugs. These in vitro platelet studies may have relevance for in vivo thrombotic conditions.

Randomised, placebo controlled trial of effect of a leukotriene receptor antagonist, montelukast, on tapering inhaled corticosteroids in asthmatic patients

OBJECTIVE

To determine the ability of montelukast, a leukotriene receptor antagonist, to allow tapering of inhaled corticosteroids in clinically stable asthmatic patients.

DESIGN

Double blind, randomised, placebo controlled, parallel group study. After a single blind placebo run in period, during which (at most) two inhaled corticosteroids dose decreases occurred, qualifying, clinically stable patients were allocated randomly to receive montelukast (10 mg tablet) or matching placebo once daily at bedtime for up to 12 weeks.

SETTING

23 academic asthma centres in United States, Canada, and Europe.

PARTICIPANTS

226 clinically stable patients with chronic asthma receiving high doses of inhaled corticosteroids (113 randomised to montelukast and 113 to placebo).

INTERVENTIONS

Every 2 weeks, the inhaled corticosteroids dose was tapered, maintained, or increased (rescue) based on a standardised clinical score.

MAIN OUTCOME MEASURES

Last tolerated dose of inhaled corticosteroids.

RESULTS

Compared with placebo, montelukast allowed significant (P=0. 046) reduction in the inhaled corticosteroid dose (montelukast 47% v placebo 30%; least square mean difference 17.6%, 95% confidence interval 0.3 to 34.8). Fewer patients on montelukast (18 (16%) v 34 (30%) placebo, P=0.01) required discontinuation because of failed rescue.

CONCLUSIONS

Montelukast reduces the need for inhaled corticosteroids among patients requiring moderate to high doses of corticosteroid to maintain asthma control.

Effects of montelukast (MK-0476); a potent cysteinyl leukotriene receptor antagonist, on bronchodilation in asthmatic subjects treated with and without inhaled corticosteroids

BACKGROUND

Cysteinyl leukotriene release in association with airway inflammation is a feature of clinical asthma. The acute effects of montelukast (MK-0476), a potent, orally administered, specific cysteinyl leukotriene receptor antagonist, on airways obstruction was assessed in patients with mild to moderately severe asthma.

METHODS

Twenty two asthmatic subjects were randomised to receive montelukast, 100 mg or 250 mg, or placebo in a double blind, three period, crossover trial. Ten of the patients were using concomitant inhaled corticosteroids.

RESULTS

Montelukast increased the forced expiratory volume in one second (FEV1) from predose baseline values compared with placebo, the percentage point differences between montelukast and placebo being 8.6% (95% CI 3.6 to 13.6) and 8.5% (95% CI 3.5 to 13.5) for the 100 mg and 250 mg doses, respectively.

CONCLUSION

Single oral doses of montelukast 100 mg and 250 mg produced significant increases in FEV1 irrespective of the concurrent use of inhaled corticosteroids in asthmatic subjects with airflow limitation.

Increased risk of antituberculosis drug-induced hepatotoxicity in individuals with glutathione S-transferase M1 'null' mutation

BACKGROUND

Pathogenesis and genetic factors influencing predisposition to antituberculosis drug (ATD)-induced hepatotoxicity are not clear. Polymorphism at the genetic locus of a drug and xenobiotic compound metabolizing enzyme, N-acetyltransferase type 2 (NAT2), is reported to be associated with the excess generation of toxic reactive metabolites. Polymorphisms at the glutathione S-transferase (GST) loci (GSTM1 and GSTT1) are involved in the detoxification of these toxic metabolites in the human body to a lesser extent. We have examined whether polymorphisms at these loci are associated with the risk of ATD-induced hepatotoxicity.

METHODS

In this case-control study, 33 pulmonary tuberculosis patients with ATD-induced hepatotoxicity and 33 pulmonary tuberculosis patients receiving ATD drugs without any evidence of hepatotoxicity were considered as cases and controls, respectively. Point mutations at NAT2 and homozygous 'null' mutations at GSTM1 and GSTT1 genes were looked into genomic DNA, isolated from peripheral blood mononuclear cells by using polymerase chain reaction (PCR).

RESULTS

The frequency of homozygous 'null' mutation at the GSTM1 gene was significantly higher among cases (n = 17, 52%) than controls (n = 8, 24%) (P < 0.05, relative risk 2.13, 95% CI: 1.25-3.10). Frequencies of mutations at GSTT1 and NAT2 genes did not differ significantly between cases and controls.

CONCLUSION

Homozygous 'null' mutation at the GSTM1 gene might predispose an individual to ATD-induced hepatotoxicity.

Montelukast, a potent leukotriene receptor antagonist, causes dose-related improvements in chronic asthma. Montelukast Asthma Study Group

The leukotrienes are known to be important mediators of bronchial asthma. The ability of montelukast, a potent and selective CysLT1 leukotriene receptor antagonist, to cause a dose-related improvement in chronic asthma was investigated in a placebo-controlled, multicentre, parallel-group study. After a two week placebo run-in period, chronic asthmatic patients with a forced expiratory volume in one second (FEV1) 40-80% predicted with > or = 15% increase (absolute value) after beta2-agonist were randomly assigned to one of four treatment groups (placebo or montelukast 2, 10, or 50 mg once daily in the evening) for a three week, double-blind treatment period. For patient-reported end-points (daytime symptom score, use of as needed inhaled beta2 agonist, asthma-specific quality of life) and frequency of asthma exacerbations, montelukast 10 and 50 mg caused similar responses, superior to 2 mg and significantly (p<0.05; linear trend test) different from placebo. All three doses caused improvements in FEV1 and morning and evening peak expiratory flow rate (PEFR) that were significantly (p<0.05) different from placebo. Differences (least square mean) between the pooled 10 and 50 mg montelukast treatment groups and placebo were: 7.1% change from baseline in FEV1, 19.23 L x min(-1) in morning PEFR, -0.29 in daytime asthma symptom score (absolute value), and -0.82 in beta2-agonist use (puff x day(-1)). The incidence of adverse experiences was neither dose-related nor different between montelukast and placebo treatments. We conclude that montelukast causes a dose-related improvement in patient-reported asthma end-points over the range 2-50 mg. Montelukast causes benefit to chronic asthmatic patients by improving asthma control end-points.

Continuous flow enzyme-catalyzed polymerization in a microreactor

Enzymes immobilized on solid supports are increasingly used for greener, more sustainable chemical transformation processes. Here, we used microreactors to study enzyme-catalyzed ring-opening polymerization of ε-caprolactone to polycaprolactone. A novel microreactor design enabled us to perform these heterogeneous reactions in continuous mode, in organic media, and at elevated temperatures. Using microreactors, we achieved faster polymerization and higher molecular mass compared to using batch reactors. While this study focused on polymerization reactions, it is evident that similar microreactor based platforms can readily be extended to other enzyme-based systems, for example, high-throughput screening of new enzymes and to precision measurements of new processes where continuous flow mode is preferred. This is the first reported demonstration of a solid supported enzyme-catalyzed polymerization reaction in continuous mode.

Effects of montelukast (MK-0476), a new potent cysteinyl leukotriene (LTD4) receptor antagonist, in patients with chronic asthma

BACKGROUND

Cysteinyl leukotrienes mediate signs and symptoms of asthma. In a double-blind, placebo-controlled, crossover study, a new potent and specific cysteinyl leukotriene (LTD4) receptor antagonist, montelukast (MK-0476), was evaluated for tolerability and clinical efficacy in patients with chronic asthma (receiving and not receiving inhaled corticosteroids).

METHODS

Twenty-nine nonsmoking patients with asthma (15 treated concomitantly with inhaled corticosteroids) with FEV1 percent predicted values between 50% to 80% received MK-0476, 200 mg, or placebo three times daily for 10 1/3 days (31 doses) in a random, crossover manner, after a 2-week, open, baseline period. Comparisons in FEV1 (mean percent change from baseline after the first and last dose), mean daily daytime asthma and nocturnal awakening scores, and mean daily beta-agonist use were made between treatment periods.

RESULTS

Montelukast, compared with placebo, caused improvements in FEV1 (mean percentage point difference of the percentage change from baseline) 3 and 4 hours after dosing on day 1 (hour 3, 9.0%; 95% confidence interval [CI] 0.53, 18.72; hour four, 10.9%; 95% CI -0.25, 20.20) and day 11 (hour 3, 14.0%; 95% CI 0.76, 31.43; hour 4, 13.4%; 95% CI 1.24, 28.83). Reductions were observed in mean daily beta-agonist use (1.0 puff/day [95% CI -1.61, -0.26]), mean daytime symptom scores, and nocturnal awakenings over the 10 1/3 day treatment period. There were no important differences between the groups receiving and those not receiving inhaled corticosteroids. Montelukast was well tolerated with no serious clinical adverse events reported.

CONCLUSIONS

In this study Montelukast, 200 mg, administered three times daily for 10 1/3 days, compared with placebo, was generally well tolerated and resulted in significant improvement in chronic asthma, irrespective of the presence of inhaled corticosteroids.

Hydrophobic, hydrophilic, and charged amino acid networks within protein

The native three-dimensional structure of a single protein is determined by the physicochemical nature of its constituent amino acids. The 20 different types of amino acids, depending on their physicochemical properties, can be grouped into three major classes: hydrophobic, hydrophilic, and charged. The anatomy of the weighted and unweighted networks of hydrophobic, hydrophilic, and charged residues separately for a large number of proteins were studied. Results showed that the average degree of the hydrophobic networks has a significantly larger value than that of hydrophilic and charged networks. The average degree of the hydrophilic networks is slightly higher than that of the charged networks. The average strength of the nodes of hydrophobic networks is nearly equal to that of the charged network, whereas that of hydrophilic networks has a smaller value than that of hydrophobic and charged networks. The average strength for each of the three types of networks varies with its degree. The average strength of a node in a charged network increases more sharply than that of the hydrophobic and hydrophilic networks. Each of the three types of networks exhibits the "small-world" property. Our results further indicate that the all-amino-acids networks and hydrophobic networks are of assortative type. Although most of the hydrophilic and charged networks are of the assortative type, few others have the characteristics of disassortative mixing of the nodes. We have further observed that all-amino-acids networks and hydrophobic networks bear the signature of hierarchy, whereas the hydrophilic and charged networks do not have any hierarchical signature.

Effect of metal ions on monolayer collapses

A Langmuir monolayer of stearic acid on pure water and in the presence of certain divalent metal ions such as Cd and Pb at pH approximately 6.5 of the subphase water collapses at constant area, while for other divalent ions such as Mg, Co, Zn, and Mn at the same subphase pH the monolayer collapses nearly at constant pressure. Films of stearic acid with Cd, Pb, Mn, and Co in the subphase (at pH approximately 6.5) have been transferred onto hydrophilic Si(001) using a horizontal deposition technique, just after and long after collapse. Electron density profiles obtained from X-ray reflectivity analysis show that a three-molecular-layer structure starts to form just after constant area collapse, where in the lowest molecular layer, in contact with the substrate, molecules are in asymmetric configuration, i.e., both hydrocarbon tails are on the same side of the metal-bearing headgroup that touches the substrate, while the molecules above the first layer are in symmetric conformation of the tails with respect to the headgroups. Further along collapse, when the surface pressure starts to rise again with a decrease in area, more layers with molecules in the symmetric configuration are added, but the coverage is poor. On the other hand, only bimolecular layers form after constant pressure collapse, with the lower and upper layers having molecules in asymmetric and symmetric configurations, respectively, and the upper molecular layer density increases with compression of the monolayer after collapse. A "Ries mechanism" for constant area collapse and a "folding and sliding mechanism" for constant pressure collapse have been proposed.

Montelukast causes prolonged, potent leukotriene D4-receptor antagonism in the airways of patients with asthma

Montelukast, a new specific oral cysteinyl LT3-receptor antagonist was evaluated for its activity in attenuating inhaled leukotriene D4 (LTD4) bronchoconstriction in patients with asthma. In two double-blind, placebo-controlled, randomized crossover studies, patients with mild asthma (forced expiratory volume in 1 second [FEV1] > or = 70%) were studied. In trial A, LTD4 challenge began 4 hours (peak plasma concentration) after a single dose of placebo or 5, 20, 100, and 250 mg montelukast. In trial B, and LTD4 challenge was started 20 hours after administration of placebo, 40 mg montelukast, or 200 mg montelukast. During each challenge, twofold increasing concentrations of LTD4 were inhaled until specific airways conductance (sGaw) decreased by at least 50% (PC50) or the highest concentration of LTD4 was inhaled. In trial A with all doses and in trial B with the 200 mg dose, bronchoconstriction was attenuated (50% fall in sGaw was not observed) up to the highest dose of LTD4 administered. In trial B, during the 40 mg period, only two of six patients exhibited a 50% fall in sGaw; PC50 ratios (montelukast 40 mg/placebo) were 18 and 45 in these two patients. These results indicate that montelukast is a highly potent and long-lasting antagonist of LTD4-induced bronchoconstriction in patients with asthma.

Isolation and characterization of nonrhizobial plant growth promoting bacteria from nodules of Kudzu (Pueraria thunbergiana) and their effect on wheat seedling growth

The leguminous vine Kudzu (Pueraria thunbergiana) is an introduction into the N. W. Himalayan region of India. Despite its value as a fodder and cover crop, little is known about the nature of the nodule microflora. In an attempt to study the nodule bacteria, we isolated and characterized three nonrhizobial plant growth promoting bacteria from surface sterilized nodules of Kudzu. Based on the sequencing of the 16 S r RNA gene, the isolates were designated as Bacillus thuringiensis KR-1, Enterobacter asburiae KR-3, and Serratia marcescens KR-4. Crystalline bodies were detected in the isolate KR-1, confirming its identity as B. thuringiensis. Under in vitro conditions, all three isolates were found to produce indole acetic acid. Other plant growth promotion attributes such as P solubilization, hydrogen cyanide production, and ammonia production varied among the isolates. All of the three isolates promoted growth and positively influenced nutrient uptake parameters of wheat seedlings.

The effect of antiplatelet drugs, heparin, and preanalytical variables on platelet function detected by the platelet function analyzer (PFA-100)

The platelet function analyzer (PFA)-100 is a newly developed instrument that provides a rapid, in vitro, quantitative measurement of platelet adhesion and aggregation in whole blood flowing through a small aperture under high shear conditions. Thirty patients undergoing percutaneous transluminal coronary angioplasty (PTCA) and ten normal individuals were included in this study. In vitro and in vivo studies were conducted to discern the effect of combinations of antiplatelet drugs (aspirin, ticlopidine, abciximab) and heparin on the performance of the device as well as the effects of preanalytical variables, such as method of sample collection and ex vivo anticoagulants. Studies were also conducted examining the effect of aperture size (standard 150 microns vs. smaller 120 microns) on the ability of the device to detect the effect of antiplatelet drugs. There was no difference in mean PFA-100 closure time with citrate versus PPACK anticoagulants or with venipuncture vs. sheath sampling. Closure times did not vary with heparin administration. Closure times were slightly longer for patients taking aspirin plus ticlopidine compared to aspirin alone (p = NS). In contrast adenosine disphosphate (ADP) induced platelet aggregation was significantly less in patients that took aspirin plus ticlopidine vs. aspirin alone (p = .0005). In vitro, there was a dose-dependent increase in closure time for both aperture sizes with increasing abciximab concentration. Although both cartridges showed infinite closure times at an abciximab concentration of 2.25 micrograms/mL, there was a slight benefit to using the 120 microns aperture cartridges at abciximab concentrations of 1.75 to 2.0 micrograms/mL. In ten patients who were followed during abciximab therapy to assess the effect of aperture size, the PFA-100 was able to detect in vivo platelet inhibition by abciximab, but detection of recovery from abciximab-induced platelet dysfunction was slightly better for the PFA-100 with the 120 microns aperture compared to the standard 150 microns aperture collagen/ADP cartridge.

Predicting developmental outcome at school age from infant tests of normal, at-risk and retarded infants

The predictive validity of developmental testing was investigated in term, preterm and retarded children. Verbal, performance and locomotor development were assessed at various ages and individual development curves constructed. Inter-age correlations between development tests at nine to 24 months and intellectual assessment at seven years revealed a strong effect on prediction for age at testing and level of mental performance. Categorisation by level of mental performance demonstrated that at seven years 98.6 per cent of the children with developmental quotients (DQs) greater than 85 at 24 months achieved IQs greater than 85, while 98.7 per cent of the seven- to eight-year-old children with DQs greater than 85 at nine to 24 months achieved IQs greater than 85. The Griffiths language and performance scores and their combination were the strongest predictors of later intellectual functioning. The social score was of moderate significance, while the locomotor score had no predictive value. Analysis of individual development curves revealed that prediction was hampered in some children by factors not detectable by statistical analysis, such as dissociations in development, organic impairment and major life events. Among the prenatal, perinatal and postnatal variables studied, only socio-economic status was of predictive significance; its effect depended on the level of mental performance and was most marked in term children, but it had no effect on retarded children.

Vitamin A as an enzyme that catalyzes the reduction of MTT to formazan by vitamin C

The tetrazolium salt 3(4,5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) is reduced to formazan by the succinate dehydrogenase system of active mitochondria, and hence, specifically used to assay for the viable cells, such as measurement of cell proliferation, cytotoxicity, and cell number. However, in the present study we have shown that some component specifically present in M199 but not in RPMI 1640 media can reduce MTT to formazan in the absence of a living system. Further study revealed that ascorbic acid reduced MTT to formazan, which was profoundly increased by a very small amount of retinol, whereas retinol alone had no effect. Oxidation of ascorbic acid by H(2)O(2) destroyed its ability to reduce MTT. The rate of MTT reduction was directly proportional to the concentration of MTT in the absence of retinol, but approached a zero-order state beyond a certain concentration of MTT in the presence of retinol. Furthermore, retinol remained unchanged after the completion of the reaction. Taken together, these results showed that retinol acts as a reductase that catalyzes the reduction of MTT to formazan using ascorbic acid as the cosubstrate (electron donor).

Reperfusion edema after lung transplantation: radiographic manifestations

PURPOSE

To characterize the radiographic manifestations of reperfusion edema after lung transplantation and to correlate the severity of the radiographic findings with pulmonary physiology.

MATERIALS AND METHODS

Chest radiographs obtained after 45 lung transplantation procedures (20 single, 25 double) were reviewed retrospectively. Physiologic parameters (alveolar-arterial gradient, ratio of partial pressure of oxygen to fraction of inspired oxygen) were noted in patients who underwent intubation.

RESULTS

Reperfusion edema appeared on day 1 in 39 transplants and by day 3 in 44. One patient's lungs remained clear. Peak severity occurred by day 4 in 43 of 44 transplants. At peak severity, reperfusion edema appeared as reticular interstitial disease in the upper (19%), middle (33%), and lower (34%) lung zones or air-space disease in the upper (31%), middle (61%), and lower (57%) zones. Reperfusion edema was asymmetric after double-lung transplantation in nine patients. The process cleared by day 10 in five transplants and by day 21 in another seven. There was a poor correlation between the severity of radiographic findings and physiologic measurements.

CONCLUSION

Reperfusion edema is almost invariable after lung transplantation and most often appears as air-space disease in the middle and/or lower lung zones. The severity of radiographic findings is a poor indicator of pulmonary physiology.

Structures of gangliosides from bovine adrenal medulla

Five gangliosides, accounting for over 95% of the total ganglioside fraction, were isolated from bovine adrenal medulla by preparative thin-layer chromatography and the carbohydrate structures determined by a combination of periodate oxidation and permethylation techniques. Partially methylated alditol acetates were generated from the neutral sugars of the fully methylated glycolipids and identified by gas-liquid chromatography. Substitution on N-acetylgalactosamine was determined by methanolysis of the permethylated ganglioside, acetylation of the products, and identification of the resulting substituted methyl glycosides by GLC. Periodate oxidation followed by borohydride reduction confirmed some of the linkages and demonstrated the absence of (2-8) linkages between sialic acid units. Mass spectrometry of the permethylated gangliosides gave information on sugar sequence at the nonreducing end.