Analytical method development, identification, and characterization of stress degradation products of idelalisib by ultrahigh-performance liquid chromatography with photodiode array and ultrahigh-performance liquid chromatography with electrospray ionization quadrupole time-of-flight mass spectrometry studies

RATIONALE

As per International Council for Harmonization (ICH) drug stability test guideline Q1A(R2), inherent stability characteristics of a drug should be studied. This work was designed to investigate inherent degradation characteristics of the drug idelalisib under ICH prescribed stress conditions, identify its degradation products, and postulate their corresponding degradation pathways.

METHODS

Idelalisib was subjected to the ICH prescribed conditions of hydrolytic (neutral, acidic, and alkaline), photolytic, oxidative, and thermal stress according to ICH guideline Q1A(R2). An ultrahigh-performance liquid chromatography with photodiode array (UHPLC-PDA) method was developed to adequately resolve the drug from its degradation products, validated as per the ICH guidelines, and subsequently extended to UHPLC with electrospray ionization quadrupole time-of-flight mass spectrometry (ESI-QTOFMS) studies to identify the degradation products.

RESULTS

Significant degradation was noted under conditions of acidic/alkaline hydrolysis, acid photolysis, and oxidative stress. The UHPLC/ESI-QTOFMS studies revealed the generation of four degradation products (I-IV), which were satisfactorily resolved from the drug by UHPLC on a Kinetex® C18 (100 × 4.6 mm; 2.6 μm) column by the developed isocratic elution method. Detection wavelength was selected as 270 nm. All the degradation products (I-IV) could be identified and characterized from their mass spectral data. The degradation pathways for the generation of various products from the drug were postulated.

CONCLUSIONS

A UHPLC-PDA method was developed and validated for idelalisib. Four degradation products of idelalisib were revealed through UHPLC/ESI-QTOFMS studies, and corresponding degradation pathways were postulated for the same.

Method validation and characterization of stress degradation products of azelastine hydrochloride using LC-UV/PDA and LC-Q/TOF-MS studies

RATIONALE

Azelastine HCl is a second-generation H1 -receptor antagonist approved by the US Food and Drug Administration (US FDA) for treating seasonal allergic rhinitis and non-allergic vasomotor rhinitis. This study encompasses the validation of a liquid chromatography-ultra violet photo diode array (LC-UV/PDA) method for the drug and its extension to liquid chromatography/quadrupole time-of-flight mass spectrometry (LC-Q/TOF-MS) studies for identification and characterization of various stress degradation products of the drug.

METHODS

Stress degradation of azelastine HCl was undertaken under the International Council for Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use (ICH) prescribed conditions of hydrolytic, photolytic, oxidative, and thermal stress. The degraded drug solutions were analyzed using Ultra Performance Liquid Chromatography (UPLC) employing a C18 (100 × 4.6 mm; 2.6 μ, Kinetex) column by isocratic elution. Detection wavelength was 241 nm. The degradation products were identified and characterized using UPLC-MS/TOF studies, and an attempt was made to isolate one of the degradation products by solvent extraction.

RESULTS

The drug was found to significantly degrade under acidic/alkaline/neutral photolytic, oxidative, and alkaline hydrolytic conditions. Six degradation products (I-VI) were identified through LC-Q/TOF-MS studies that were adequately resolved from the drug with the developed UPLC method. All degradation products (I-VI) were ionized in the total ion chromatogram (TIC) in the LC-MS studies, and these were identified and characterized, and the degradation pathway of the drug was postulated. One of the oxidation products isolated from the degraded drug solution was characterized through differential scanning calorimetry, Fourier-transform infrared spectroscopy, and nuclear magnetic resonance spectral data.

CONCLUSIONS

Six degradation products generated from stress degradation studies on azelastine HCl were adequately resolved through LC-UV/PDA studies followed by method validation. These were successfully identified and characterized through LC-Q/TOF-MS studies, and the degradation pathways for the generation of these products from the drug have been postulated.

Identification and characterization of stress degradation products of ibrutinib by LC-UV/PDA and LC-Q/TOF-MS studies

The anticancer drug ibrutinib was subjected to stress degradation studies under the ICH-prescribed hydrolytic, photolytic, oxidative and thermal stress conditions, and its degradation behavior was studied. A significant degradation was noted for the drug under acidic/alkaline hydrolytic, acid/alkaline photolytic, and oxidative conditions. The UPLC-UV/PDA studies revealed the generation of six degradation products (I-VI), and these were adequately resolved from the drug under the developed chromatographic conditions over a Kinetex® C18 (100 mm×4.6 mm; 2.6 μm) column employing isocratic elution method. Detection wavelength was selected as 289 nm. The UPLC-UV/PDA method conditions were extrapolated to UPLC-MS/TOF studies. All the six degradation products were found to be ionized in the total ion chromatogram, and the products could be identified and characterized from their mass spectral data. The possible degradation route of ibrutinib leading to generation of various products was also postulated.

Identification and characterization of stress degradation products of febuxostat employing ultra-performance liquid chromatography-ultraviolet/photodiode array and liquid chromatography-mass spectrometry/time-of-flight studies

RATIONALE

Febuxostat (FEB) is a xanthine oxidase inhibitor approved by the U.S. Food and Drug Administration for long-term treatment of gout and hyperuricemia. There were no reports on identification and characterization of stress degradation products of the drug.

METHODS

FEB was subjected to forced decomposition conditions such as hydrolysis (neutral, acidic, and alkaline), oxidation, photolysis, and thermal stress, per the ICH guideline Q1A(R2). The degradation products formed were subjected to ultra-performance liquid chromatography (UPLC) on a C18 Kinetex column (100 × 4.6 mm, 2.6 μm) using isocratic elution method. Detection wavelength was 317 nm. The developed method was extended to UPLC-mass spectrometry/time of flight (MS/TOF) studies to identify and characterize the degradation products.

RESULTS

The drug exhibited significant degradation under alkaline/neutral hydrolytic, alkaline/acidic photolytic, and oxidative conditions, whereas it remained stable under acid hydrolytic, neutral photolytic, and thermal conditions. In total, eight degradation products (I-VIII) were formed, which could be adequately determined from the drug using the developed UPLC method. Of the eight degradation products identified from the liquid chromatography-ultraviolet (LC-UV) chromatogram, five (III and IV and VI-VIII) could be characterized using their MS/TOF spectral data. The degradation pathway leading to the formation of the products was postulated, and this is not reported so far.

CONCLUSIONS

Forced degradation studies were conducted on FEB, and the degradation products produced were identified by their mass spectral data obtained using LC-MS studies.

Right ventricular and left ventricular diameters are independent predictors of death or cardiopulmonary resuscitation in intermediate and high-risk pulmonary embolisms

Background

Increased right ventricular (RV) dilation measured by the ratio of RV diameter (RVD) to left ventricular (LV) diameter (LVD) (RV:LV) is associated with pulmonary embolism (PE) severity and mortality. Data regarding the individual contributions of RVD and LVD are limited.

Purpose

To examine RVD and LVD as independent contributors to death or need for cardiopulmonary resuscitation (CPR) in intermediate- or high-risk PEs treated with surgical or catheter-based strategies

Methods

We measured basal RVD and LVD on presenting transthoracic echocardiograms (TTE) using the diastolic 4-chamber view on 127 PEs managed with surgical embolectomy (n=95, 75%), extracorporeal membrane oxygenation (n=23, 18%), or catheter-directed embolectomy (n=9, 7%) for intermediate- (64%) or high-risk (36%) PE (based on European Society of Cardiology criteria) between 2005 and 2022. The primary outcome was the composite of death (n=2) or survivors requiring CPR (n=10).

Results

A total of 127 patients were analyzed. Subjects were 57±14 years, 38% women, BMI 34±8. Mean RVD and LVD were 4.4±0.9 cm and 3.9±0.8 cm respectively. All presented with severe RV dysfunction on TTE and elevated cardiac biomarkers (Troponin-I or B-type natriuretic peptide). Mean RV:LV was 1.2±0.3 (range 0.7 to 2.8). Using logistic regression, higher RV:LV was associated with increased odds of death or CPR (odds ratio (OR) 15 [95% confidence interval (CI): 2.5, 82] per 1-unit increase, p=0.002. RV:LV >1.2 was the cutoff most associated with death or CPR, OR 7.2 [95% CI: 1.5, 34.5], p=0.01. Increasing RVD [OR 3.8 (95% CI: 1.1, 12.8), p=0.03] and decreasing LVD [OR 4.9 (95% CI: 1.3, 16.9), p=0.02] were independent predictors of death or CPR. RVD >5.0 cm (OR 5.9 [95% CI: 1,5, 23.2], p 0.01) and LVD <3.6 cm (OR 7.0 [95% CI: 1.7, 27.9], p=0.006) were the cutoff values most associated with the primary outcome. These cutoff values remained significant predictors even after adjustment for body surface area. Other parameters or RV size and function (diastolic area, systolic area and fractional area change) did not predict death or CPR. All of the subjects meeting the primary outcome had high-risk PE.

Discussion

In addition to RV:LV greater than 1.2, RVD and LVD were independently associated with death or CPR among high- or intermediate risk PEs. The independent contribution of declining LVD on PE mortality is a novel finding and highlights PE associatient LV pathophysiology (hyperdynamic and underfilled) antecedent to hemodynamic collapse. PE literature focuses on RV dilation as a predictor of PE mortality. LVD may represent a useful measure to risk stratify PE patients and predict hemodynamic decompensation.

Funding Acknowledgement

Type of funding sources: None.

Role of artificial intelligence in fast-track drug discovery and vaccine development for COVID-19

COVID-19 is a global pandemic spread across more than 200 countries and several measures are being taken to control it. Researchers in pharmaceutical academia/industry are incessantly targeting this disease through vaccine and drug development protocols. Artificial intelligence is being extensively explored for surveillance, diagnostics, contact tracing, and for clinical management of COVID-19. The most common application has been for repurposing of existing drugs through various AI tools. Successful training of artificial neural networks based on identification of specific patterns in binding of known antiviral drugs with protein sequences from diverse virus species have generated models giving good predictions for molecules against SARS-CoV-2 virus, in sync with clinical studies. ML tools have also been used to investigate immunogenic components of the virus to be exploited as vaccine candidates. In this chapter, the utilization of artificial intelligence to accelerate drug-design and vaccine design research for COVID-19 has been reviewed.

One Pot Synthesis and Pharmacological Evaluation of Aryl Substituted Imidazoles as Potential Atypical Antipsychotics

Background:

Second generation or “atypical” antipsychotics demonstrate an improved therapeutic profile over conventional neuroleptics. These are effective in both positive and negative symptoms of the disease and have a lower propensity to induce adverse symptoms.

Objective:

The main objective of the research was in silico design and synthesis of potential atypical antipsychotics with combined antiserotonergic / antidopaminergic effect.

Methods:

A one pot synthesis of aryl substituted imidazole derivatives was carried out in green solvent PEG-400 and the prepared compounds were evaluated for atypical antipsychotic activity in animal models for dopaminergic and serotonergic antagonism. The compounds were designed based on their 3D similarity studies to standard drugs and in silico (docking studies) with respect to 5-HT2A and D2 receptors.

Results:

Results from the docking studies with respect to 5-HT2A and D2 receptors suggested a potential atypical antipsychotic profile for the test compounds. Theoretical ADME profiling of the compounds based on selected physicochemical parameters suggested an excellent compliance with Lipinski’s rules. The potential of these compounds to penetrate the blood brain barrier (log BB) was computed through an online software program and the values obtained for the compounds suggested a good potential for brain permeation. Reversal of apomorphine induced mesh climbing behaviour coupled with inactivity in the stereotypy assay indicates antidopaminergic effect and a potential atypical profile for the test compounds 1-5. Further, the activity of compounds in DOI assay indicated a 5-HT2 antagonistic profile (5-HT2 antagonism).

Conclusion:

Compound 5 emerged as important lead compound showing combined antidopaminergic and antiserotonergic (5-HT2A) activity with a potential atypical antipsychotic profile.

Design and Synthesis of Novel Anti-inflammatory/Anti-ulcer Hybrid Molecules with Antioxidant Activity

BACKGROUND

NSAIDs are the most widely prescribed medications worldwide for their anti-inflammatory, antipyretic, and analgesic effects. However, their chronic use can lead to several adverse drug events including GI toxicity. The selective COX-2 inhibitors developed as gastrosparing NSAIDs also suffer from serious adverse effects which limit their efficacy.

OBJECTIVE

Local generation of reactive oxygen species is implicated in NSAID-mediated gastric ulceration and their combination with H2 antagonists like famotidine reduces the risk of ulcers. The objective of this work was to design and synthesize novel methanesulphonamido isoxazole derivatives by hybridizing the structural features of NSAIDs with those of antiulcer drugs (ranitidine, famotidine, etc.) to utilize a dual combination of anti-inflammatory activity and reducing (antioxidant) potential.

METHODS

The designing process utilized three dimensional similarity studies and utilized an isoxazole core having a potential for anti-inflammatory as well as radical scavenging antioxidant activity. The compounds were assayed for their anti-inflammatory activity in established in vivo models. The in vitro antioxidant activity was assessed in potassium ferricyanide reducing power (PFRAP) assay employing ascorbic acid as the standard drug.

RESULTS

Compounds 5, 6, 9 and 10 showed antiinflammatory activity comparable to the standard drugs and were also found to be non-ulcerogenic at the test doses. Compounds 6-10 exhibited good antioxidant effect in the concentration range of 1.0- 50.0 μmol/ml. The test compounds were also found to comply with the Lipinski rule suggesting good oral absorption.

CONCLUSION

A new series of isoxazole based compounds is being reported with good antiinflammatory activity coupled with antioxidant potential as gastro-sparing anti-inflammatory agents.

Synthesis and Evaluation of Substituted Aryl Thiazoles With Antioxidant Potential as Gastro-sparing Anti-inflammatory Agents

Background:

NSAIDs are used as first-line drugs for the treatment of various inflammatory disorders. Chronic use of NSAIDs is known to be associated with gastrointestinal and renal toxicity. Local generation of reactive oxygen species finally resulting in cellular apoptosis is one of the accepted mechanisms for NSAID-induced toxicity.

Objective:

The objective of the present study was to design and synthesize a series of 2-methane sulfonamido substituted arylthiazole derivatives by including structural features of combined antiulcer and anti-inflammatory activity utilizing as the structural core, thiazole nucleus with potential for antioxidant effect.

Methods:

Compounds were designed based on three dimensional and field similarity studies. The synthesized compounds were evaluated for their anti-inflammatory activity in carrageenan-induced rat paw edema model. Rofecoxib and indomethacin were taken as standard drugs for comparison. The in vitro antioxidant activity was assessed in potassium ferricyanide reducing power (PFRAP) assay employing ascorbic acid as the standard drug.

Results:

The compounds 6 and 7 showed good anti-inflammatory activity comparable to the standard group and were also non ulcerogenic at the test doses. Compounds 1-7 displayed varying degrees of reducing power in the PFRAP) assay and the methanesulphonamido derivatives 4-7 showed the highest antioxidant activity (EC50 values 3.7-5.1 μmol/ml vs ascorbic acid 7.4 μmol/ml). Theoretical ADME profiling of the compounds based on selected physicochemical properties showed excellent compliance with Lipinski’s rule.

Conclusion:

A series of compounds have been designed and synthesized having dual antioxidant and anti-inflammatory activity with activities comparable to standard drugs.

Synthesis and Evaluation of Aryl Substituted Propyl Piperazines for Potential Atypical Antipsychotic Activity

BACKGROUND

Schizophrenia is a disorder with complex etiology with hyperdopaminergia as the leading underlying cause. Atypical antipsychotics are the agents which do not give rise to significant extrapyramidal side effects and are more effective against negative symptoms of schizophrenia.

INTRODUCTION

A new series of chloro-substituted substituted aryloxypiperazine derivatives and their indole based derivatives was designed and evaluated for atypical antipsychotic activity based on established models for combined dopaminergic and serotonergic antagonism.

METHODS

The present series of compounds were designed based on 3D similarity studies, synthesized and evaluated for atypical antipsychotic activity in animal models for combined dopaminergic and serotonergic antagonism. The blood-brain barrier penetration potential was assessed from theoretical log BB values computed through an online software program.

RESULTS

Theoretical ADME profiling of the designed compounds based on selected physicochemical parameters suggested excellent compliance with Lipinski's rules. The log BB values obtained for the compounds suggested a good potential for brain permeation. Indole substitution contributed towards an improved efficacy over aryloxy analogs. Lead compounds showed a potential for combined dopaminergic and serotonergic antagonism.

CONCLUSION

The 5-methoxy indole based compounds 16 and 17 were identified as the lead compounds displaying a potential atypical antipsychotic profile.

Bioanalytical Method Validation for Dronedarone and Duloxetine in Blood Serum

The present work relates to the development and validation of reversed-phase HPLC-UV-photodiode array methods for the estimation of two drugs in blood serum: dronedarone hydrochloride (DDN), a class III antiarrhythmic drug, and duloxetine hydrochloride (DLX), an antidepressant. Chromatographic analysis of DLX was carried out on a Nucleodur C18 column (250 × 4.6 mm, 5 μm) using ammonium acetate buffer (32 mM, pH 5.5) and acetonitrile (40 + 60, v/v; flow rate of 1.0 mL/min; detection wavelength of 290 nm) as the mobile phase. A Waters XTerra C18 column (250 × 4.6 mm, 5 μm) was used for the chromatographic analysis of DDN using an acetonitrile-ammonium formate buffer (20 mM, pH 3.0, with formic acid; 45 + 55, v/v; flow rate 1.0 mL/min) as the mobile phase. Pentazocine and bupropion HCl were used as the internal reference standards for DLX and DDN, respectively. Excellent linearity was observed for DLX (r2 = 0.9996; concentration range 0.2-10.0 μg/mL) and DDN (r2 = 0.9997; concn. range 2.0-50.0 μg/mL). The LODs for DLX and DDN were 0.022 and 0.78 μg/mL, respectively, and the LOQs 0.066 and 2.4 μg/mL, respectively.

"I'm 100% for it! I'm a convert!": women's experiences of a yoga programme during treatment for gynaecological cancer; an interpretative phenomenological analysis

OBJECTIVES

To explore patients' experiences of taking part in a yoga intervention while undergoing treatment for gynaecological cancer.

DESIGN

Sixteen women (age range 31-79 years; mean age 60) participated in focus groups based on a semi-structured question schedule. Resulting discussions were audio-recorded, transcribed verbatim and analysed using interpretative phenomenological analysis (IPA).

SETTING

Royal Derby Hospital, UK.

INTERVENTIONS

Patients took part in a 10-week course of Hatha yoga, where they participated in a one hour long class per week.

RESULTS

Three themes emerged from the data: applying breathing techniques, engaging in the physicality of yoga and finding a community. The first theme was particularly important to the patients as they noted the breadth and applicability of the techniques in their day-to-day lives. The latter two themes reflect physical and social perspectives, which are established topics in the cancer and yoga literature and are contextualised here within the women's experiences of cancer treatment.

CONCLUSIONS

The women's perceptions of the programme were generally positive, providing a previously unseen view of the patient experience of participating in a yoga intervention. The difference between the women's prior expectations and lived experiences is discussed.

Thermoelectric properties of Bi-added Co4Sb12 skutterudites

Void filling in (I) Bi(x)-added Co(4)Sb(12) or (II) Sb/Bi substitution of Co(4)Sb(12-x)Bi(x) has been investigated for structural and thermoelectric properties evaluation. X-ray powder data Rietveld refinements combined with electron probe microanalyses showed a polycrystalline and practically Bi-free CoSb(3) skutterudite phase as the major constituent as well as a secondary Bi phase in the grain boundaries. For series I alloys, the electrical conductivity, Seebeck coefficient and thermal conductivity were measured as a function of temperature in the range from 450 to 750 K. The electrical conductivity of all the samples increased with increasing temperature, showing a semiconducting nature with smaller values of the Seebeck coefficient for higher Bi fractions. Conduction over the entire temperature range was found to arise from a single p-type carrier. Thermal conductivity showed a reduction with Bi added in all the samples, except for Bi(0.75)Co(4)Sb(12), and the lowest lattice thermal conductivity was found for a Bi-added fraction of 0.5. The maximum zT value of 0.53 at 632 K is higher than that of Co(4)Sb(12).

A novel method for spectrophotometric determination of pregabalin in pure form and in capsules

Background

Pregabalin, a γ-amino-n-butyric acid derivative, is an antiepileptic drug not yet official in any pharmacopeia and development of analytical procedures for this drug in bulk/formulation forms is a necessity. We herein, report a new, simple, extraction free, cost effective, sensitive and reproducible spectrophotometric method for the determination of the pregabalin.

Results

Pregabalin, as a primary amine was reacted with ninhydrin in phosphate buffer pH 7.4 to form blue violet colored chromogen which could be measured spectrophotometrically at λ_max 402.6 nm. The method was validated with respect to linearity, accuracy, precision and robustness. The method showed linearity in a wide concentration range of 50-1000 μg mL^-1 with good correlation coefficient (0.992). The limits of assays detection was found to be 6.0 μg mL^-1 and quantitation limit was 20.0 μg mL^-1. The suggested method was applied to the determination of the drug in capsules. No interference could be observed from the additives in the capsules. The percentage recovery was found to be 100.43 ± 1.24.

Conclusion

The developed method was successfully validated and applied to the determination of pregabalin in bulk and pharmaceutical formulations without any interference from common excipients. Hence, this method can be potentially useful for routine laboratory analysis of pregabalin.

Molecular-Field-Based Three-Dimensional Similarity Studies on Quinoline-Based CNS Active Agents

A series of quinoline-based agents with CNS activity have been analyzed for their three-dimensional similarity with respect to a set of standard atypical antipsychotics. The method aligns the molecules based on their molecular fields represented as local extrema of electrostatic, van der Waals, and hydrophobic potentials of the molecule termed “field points.” The compounds in the series were found to demonstrate relatively lesser 3D similarity to the dibenzodiazepine derivative clozapine. Similarity values were higher with respect to extended chain compounds ketanserin, ziprasidone, and risperidone. The results obtained were found to agree with the physicochemical similarity of the compounds reported earlier.

Pre-treatment white blood cell subtypes as prognostic indicators in ovarian cancer

OBJECTIVE

Inflammatory cells can both suppress and stimulate tumour growth and their influence on clinical outcome in cancer patients has been studied in various cancer types. Here we have investigated their influence on outcome in primary epithelial ovarian cancer.

STUDY DESIGN

Serum white blood cell numbers according to subtype were recorded prior to treatment in 136 patients with primary epithelial ovarian cancer. Their correlation with overall survival and disease-free survival was analysed using both univariate and multivariate analysis adjusting for the known prognostic factors (age, stage and debulking status).

RESULTS

Multivariate analysis demonstrated that a lower lymphocyte fraction of total white blood cells was significantly associated with mortality (p<0.01). On univariate analysis (p=0.0027, HR=1.15), and multivariate analysis of those patients who were optimally debulked (p=0.036, HR=1.17), a higher monocyte count was significantly associated with recurrence. On multivariate analysis amongst those who were suboptimally debulked, a higher eosinophil count was predictive of both recurrence (p=0.0037, HR=1.77) and mortality (p=0.033, HR=1.73).

CONCLUSION

High monocyte counts amongst those who were optimally debulked independently predict adverse outcome in primary epithelial ovarian cancer.

A distinct molecular profile associated with mucinous epithelial ovarian cancer

Mucinous epithelial ovarian cancers (MOC) are clinically and morphologically distinct from the other histological subtypes of ovarian cancer. To determine the genetic basis of MOC and to identify potential tumour markers, gene expression profiling of 49 primary ovarian cancers of different histological subtypes was performed using a customised oligonucleotide microarray containing >59 000 probesets. The results show that MOC express a genetic profile that both differs and overlaps with other subtypes of epithelial ovarian cancer. Concordant with its histological phenotype, MOC express genes characteristic of mucinous carcinomas of varying epithelial origin, including intestinal carcinomas. Differences in gene expression between MOC and other histological subtypes of ovarian cancer were confirmed by RT–PCR and/or immunohistochemistry. In particular, galectin 4 (LGALS4) was highly and specifically expressed in MOC, but expressed at lower levels in benign mucinous cysts and borderline (atypical proliferative) tumours, supporting a malignant progression model of MOC. Hence LGALS4 may have application as an early and differential diagnostic marker of MOC.

Design, synthesis, and evaluation of novelly substituted benzimidazole compounds as angiotensin II receptor antagonists

5-Nitrobenzimidazole derivatives with varying substituents at 2-position have been designed, synthesized, and evaluated for angiotensin II antagonistic activity. A drug-receptor interaction model has been proposed.

The effect of the preemptive use of the NMDA receptor antagonist dextromethorphan on postoperative analgesic requirements

Both central sensitization after peripheral tissue injury and the development of opiate tolerance involve activation of N-methyl-D-aspartate receptors. In this double-blinded, randomized study, we investigated the preemptive versus postincisional effects of dextromethorphan, an N-methyl-D-aspartate receptor antagonist, on postoperative pain management. Sixty ASA I and II patients undergoing elective upper abdominal surgery were randomly allocated to three equally sized groups. The Preincisional group patients received dextromethorphan (120 mg) IM 30 min before skin incision and a placebo (isotonic saline) 30 min before the end of surgery. The Postincisional group received the same dose of dextromethorphan 30 min before the end of surgery and a placebo 30 min before skin incision, and the Control group received a placebo both 30 min before skin incision and 30 min before the end of surgery. A standard general anesthetic technique including fentanyl, propofol, isoflurane, and atracurium was used. Postoperative meperidine patient-controlled analgesia (PCA) was used. There were no significant group differences in the median pain scores except in the visual analog scale at 6 h both at rest and on movement; these were significantly lower in the Preincisional group than the other two groups (P < 0.05). The mean time to initiation of PCA was significantly longer in the Preincisional than in the Postincisional and Control groups (mean [SD]: 10.7 [2.2 h], 5.4 [2.1 h], and 3.7 [1.6 h], respectively; P < 0.001]. The 24-h PCA-meperidine consumption was significantly less in the Preincisional than in the Postincisional and Control groups (mean [SD]: 140 [60 mg], 390 [80 mg], and 570 [70 mg], respectively; P < 0.001]. The incidence of postoperative hypoxemia (SpO(2) < 90%) and nausea was significantly less in the Preincisional group (P < 0.05). In conclusion, preincisional IM 120 mg dextromethorphan compared with the same postincisional dose significantly reduced postoperative meperidine consumption.

IMPLICATIONS

IM administration of preincisional dextromethorphan (120 mg), allowing the use of a larger dose sufficient to block the central sensitization caused by activation of the N-methyl-D-aspartate receptors, provides preemptive analgesia and has a supportive role in postoperative pain relief, as shown by a significant decrease in 24-h meperidine consumption.

Blood meal identification by using Microdot ELISA in vector mosquitoes

The blood meals of five mosquito species which are vectors for malaria, J.E. and Filaria were determined by using Microdot ELISA technique, which is a rapid and sensitive method. A total of 4354 freshly fed mosquitoes comprising of Anopheles culicifacies, An stephensi, Culex quinquefasciatus, Cx. vishnui gp. and Cx. tritaeniorhynchus were tested. Results of the study reveal that highest proportion of An. culicifacies between 76-100% fed on bovine host followed by 0.3 to 24.2% on human. Cx. vishnui showed 1.9% feeding on human, 49-87.7% on bovine and 7.4-12.3% on the pigs. It has been observed that malaria vectors namely An. culicifacies and An. stephensi are still zoophilic in nature. Similarly, the vector of J.E. namely Culex vishnui gp. and Cx. tritaeniorhynchus also fed on cattle but some samples have indicated feeding of blood meal from pigs.

Molecular and immunological analysis of an ABC transporter complex required for cytochrome c biogenesis

The helABC genes are predicted to encode an ATP-binding cassette (ABC) transporter necessary for heme export for ligation in bacterial cytochrome c biogenesis. The recent discoveries of homologs of the helB and helC genes in plant mitochondrial genomes suggest this is a highly conserved transporter in prokaryotes and some eukaryotes with the HelB and HelC proteins comprising the transmembrane components. Molecular genetic analysis in the Gram-negative bacterium Rhodobacter capsulatus was used to show that the helABC and helDX genes are part of an operon linked to the secDF genes. To facilitate analysis of this transporter, strains with non-polar deletions in each gene, epitope and reporter-tagged HelABCD proteins, and antisera specific to the HelA and HelX proteins were generated. We directly demonstrate that this transporter is present in the cytoplasmic membrane as an HelABCD complex. The HelB and HelC but not HelD proteins are necessary for the binding and stability of the HelA protein, the cytoplasmic subunit containing the ATP-binding region. In addition we show that the HelA protein co-immunoprecipitates with either the HelC or HelD proteins. Thus, the HelABCD heme export complex is distinguished by the presence of four membrane-associated subunits and represents a unique subfamily of ABC transporters.

Excretion of ammonium by a nifL mutant of Azotobacter vinelandii fixing nitrogen

A mutation in the gene upstream of nifA in Azotobacter vinelandii was introduced into the chromosome to replace the corresponding wild-type region. The resulting mutant, MV376, produced nitrogenase constitutively in the presence of 15 mM ammonium. When introduced into a nifH-lacZ fusion strain, the mutation permitted beta-galactosidase production in the presence of ammonium. The gene upstream of nifA is therefore designated nifL because of its similarity to the Klebsiella pneumoniae nifL gene in proximity to nifA, in mutant phenotype, and in amino acid sequence of the gene product. The A. vinelandii nifL mutant MV376 excreted significant quantities of ammonium (approximately 10 mM) during diazotrophic growth. In contrast, ammonium excretion during diazotrophy was much lower in a K. pneumoniae nifL deletion mutant (maximum, 0.15 mM) but significantly higher than in NifL+ K. pneumoniae. The expression of the A. vinelandii nifA gene, unlike that of K. pneumoniae, was not repressed by ammonium.

The product of the nitrogen fixation regulatory gene nfrX of Azotobacter vinelandii is functionally and structurally homologous to the uridylyltransferase encoded by glnD in enteric bacteria

We sequenced the nitrogen fixation regulatory gene nfrX from Azotobacter vinelandii, mutations in which cause a Nif- phenotype, and found that it encodes a 105-kDa protein (NfrX), the N terminus of which is highly homologous to that of the uridylyltransferase-uridylyl-removing enzyme encoded by glnD in Escherichia coli. In vivo complementation experiments demonstrate that the glnD and nfrX products are functionally interchangeable. A vinelandii nfrX thus appears to encode a uridylyltransferase-uridylyl-removing enzyme, and in this paper we report the first sequence of such a protein. The Nif- phenotype of nfrX mutants can be suppressed by a second mutation in a recently identified nifL-like gene immediately upstream of nifA in A. vinelandii. NifL mediates nif regulation in response to the N status in A. vinelandii, presumably by inhibiting NifA activator function as occurs in Klebsiella pneumoniae; thus, one role of NfrX is to modify, either directly or indirectly, the activity of the nifL product.

Effect of phospholipid structure on stability and survival times of liposomes in circulation

The phosphatidylcholine (PC) component of liposomes was structurally modified by replacing its C-1, or both C-1 and C-2, ester linkage(s) with an ether and/or carbamyl bond(s) or by changing its steric configuration. Small unilamellar liposomes were formed from PC, traces of the corresponding 14C-labeled PC and cholesterol in the presence of 6-carboxyfluorescein (02.M) by sonication, and purified by centrifugation. These liposomes were administered intravenously to rats, and their stability in blood as well as the rate of their clearance from the circulation were determined. Stability and survival times of liposomes were markedly increased by modifying both the C-1 and the C-2 ester linkages in PC. A similar but quantitatively smaller effect was observed when only the C-1 ester linkage was modified. However, the stability remained unaffected by changing the steric configuration of PC, but this modification influenced the clearance rate of liposomes from the circulation. These results demonstrate that both stability in blood and the clearance rate from circulation can be modulated by structurally modifying the ester linkages in the phospholipid component of liposomes.

Protection of mice against Plasmodium berghei infection by a tuftsin derivative

In Plasmodium berghei infections, the mortality rate and parasitaemias were significantly reduced and the mean survival time was considerably enhanced by pretreating the animals with a tuftsin derivative, Thr-Lys-Pro-ARg-NH-(CH2)2-NHCOC15H31. This effect of the modified tuftsin was further increased upon its incorporation in the liposome bilayer. These results indicate that tuftsin and its derivatives may prove useful in enhancing nonspecific host resistance against protozoan infections.

Influence of the phospholipid structure on the stability of liposomes in serum

The effect of serum on the structural integrity of liposomes consisting of ether and/or carbamyl analogs of 1,2-diester phosphatidylcholine (PC) has been evaluated by measuring both the efflux of the entrapped 6-carboxyfluorescein and the lipid transfer to serum proteins, and the results have been compared with the egg PC liposomes. Replacement of the C-1 ester bond in PC by an ether linkage did not significantly enhance the liposome stability, but it was markedly increased upon introducing further structural changes in the C-2 ester region of the resulting 1-ether-2-ester PC. However, the stability was not influenced by altering the steric configuration of the latter phospholipid. These results strongly suggest that lysis of liposomes in serum can be prevented by structurally modifying the ester bond(s) in the phospholipid component of liposomes.

Antibody-mediated targeting of liposomes to erythrocytes in whole blood

F(ab')2 fragments derived from anti-rat erythrocyte antibody or normal rabbit serum IgG were covalently attached to the surface of liposomes consisting of equimolar amounts of egg phosphatidylcholine and cholesterol. These liposomes were interacted with rat, monkey or mouse blood, and their binding to both red and white blood cells was determined. Results of these studies show that coupling of liposomes to anti-rat erythrocyte F(ab')2 considerably enhances their binding to erythrocytes in rat blood. However, no such increase in the binding was observed with rat leukocytes or monkey and mouse erythrocytes. Besides, the interactions between the liposomes and target cells did not affect the permeability properties of the liposome bilayer. These observations indicate that liposomes coupled to cell-specific antibodies may serve as highly useful carriers for homing of drugs/enzymes to specific cells in biophase.

Phase behavior of carbamyloxyphosphatidylcholine, a sphingolipid analogue

The phase behavior of two series of phosphatidylcholines (PC) possessing carbamyloxy-linked fatty acids has been studied by differential scanning calorimetry. These non-natural phosphatidylcholines are of interest because they possess the capability of forming interlipid hydrogen bonds via the carbamyloxy function and as such can serve as a model for sphingolipids, the phase behavior of which is thought to be dominated by interlipid hydrogen bonding. Furthermore, carbamyloxyphosphatidylcholines form unusually stable liposomes, and thus have potential in drug delivery. Carbamyloxyphosphatidylcholines of the type di-(CnH2n+1NHCOO)-PC, where n = 13, 15, or 17, exhibit metastable polymorphism. Cooling from the liquid crystalline state results in formation of a metastable low-temperature polymorph I, which must transform into a stable low-temperature polymorph II before the liquid crystalline state can be reached again. Carbamyloxyphosphatidylcholines of the type 1-C16:0-2-(CnH2n+1NHCOO)-PC exhibit similar metastable polymorphism. This metastability is similar to that exhibited by certain cerebrosides and sphingomyelins and indicates that the sphingosine backbone is not a prerequisite for this type of metastability. Furthermore, the carbamyloxy group is reversed in orientation compared with the amide of sphingolipids (-NHCO- versus -CONH-), suggesting that the intermolecular hydrogen bonding potential, rather than some highly specific steric or conformational constraint, is responsible for the observed metastability of sphingolipids.

Specific interactions of liposomes with PMN leukocytes upon incorporating tuftsin in their bilayers

Incorporation of tuftsin derivatives, Thr-Lys-Pro-Arg-NH-C18H37 or Thr-Lys-Pro-Arg-NH-(CH2)2-NH-COC15H31, into an egg phosphatidylcholine/cholesterol liposome bilayer led to significantly enhanced binding of the liposomes to PMN leukocytes at 37 degrees C but not at 0 degree C. Under identical conditions, no such enhanced binding of the liposomes was observed with erythrocytes and lymphocytes. These results demonstrate that grafting of tuftsin on the liposome bilayer enables the liposome to recognize specifically the PMN leukocytes and to deliver its contents to these cells.

Cimetidine - antacid combination as premedication for elective Caesarean section

The effect of premedication with an oral antacid (magnesium trisilicate), oral cimetidine or a combination of both was studied in 80 patients undergoing elective Caesarean section. Twenty patients served as untreated controls. Seventy per cent of the patients were in the high risk range for acid aspiration pneumonitis (pH less than 2.5 plus gastric content volume greater than 25 ml). Antacid therapy was effective in raising pH but the gastric volume remained high in 50 per cent of the patients. Cimetidine was effective in decreasing gastric volume and raising pH but the pH was still less than 2.5 in two patients. None of the patients given the cimetidine-antacid combination were in the high risk range for acid aspiration pneumonitis. The combination of an oral dose of cimetidine 400 mg, three to four hours before the operation followed by 20 ml of magnesium trisilicate one hour preoperatively proved to be the most efficacious regimen for prophylaxsis against Mendelson's syndrome in elective Caesarean section. Recent reports have suggested that non-particulate antacids (e.g., sodium citrate) may be preferable to particulate antacids such as magnesium trisilicate.

Prolonged small-intestinal transit time in cystic fibrosis

A lactulose hydrogen breath test was performed on 10 patients with cystic fibrosis and 15 control subjects matched for age and sex. All normal subjects had a fasting breath hydrogen concentration of less than 20 ppm. In contrast, seven of the patients with cystic fibrosis had high concentrations (25-170 ppm), which fell to 20 ppm or below on prolonged fasting (14-23 hours). Two patients showed no rise in breath hydrogen concentrations after lactulose, and in one patient the breath hydrogen concentration rose at 15 minutes, suggesting bacterial colonisation of the small bowel. Seven of the patients had prolonged small-bowel transit times (160-390 minutes) compared with those in the control group (50-150 minutes).

Maternal and fetal effects of continuous lumbar epidural analgesia for labour and delivery in pre-eclamptic patients

The effects of continuous lumbar epidural analgesia for normal labour were studied in 28 women with pre-eclampsia and in 15 normal women who served as control. Maternal hemodynamics, acid-base and blood gas findings were examined. Newborn infants were assessed by Apgar Scores together with umbilical vein and artery blood gas and acid-base values. Mild significant reduction in maternal mean arterial blood pressure occurred in the pre-eclamptic patients which was corrected easily by intravenous crystalloid infusion. Maternal and newborn acid-base and blood gas findings showed no significant changes between the pre-eclamptic and control groups. Apgar Scores in both groups were good. The study indicates that continuous epidural analgesia is a useful form of therapy in the management of normal labour in women with pre-eclampsia.