Comparative Study between Tramadol and Dexamethasone as an admixture to Bupivacaine in Supraclaivcular Brachial Plexus Block

Abstract

De novo biosynthesis of sterols and fatty acids in the Trypanosoma brucei procyclic form: Carbon source preferences and metabolic flux redistributions

De novo biosynthesis of lipids is essential for Trypanosoma brucei, a protist responsible for the sleeping sickness. Here, we demonstrate that the ketogenic carbon sources, threonine, acetate and glucose, are precursors for both fatty acid and sterol synthesis, while leucine only contributes to sterol production in the tsetse fly midgut stage of the parasite. Degradation of these carbon sources into lipids was investigated using a combination of reverse genetics and analysis of radio-labelled precursors incorporation into lipids. For instance, (i) deletion of the gene encoding isovaleryl-CoA dehydrogenase, involved in the leucine degradation pathway, abolished leucine incorporation into sterols, and (ii) RNAi-mediated down-regulation of the SCP2-thiolase gene expression abolished incorporation of the three ketogenic carbon sources into sterols. The SCP2-thiolase is part of a unidirectional two-step bridge between the fatty acid precursor, acetyl-CoA, and the precursor of the mevalonate pathway leading to sterol biosynthesis, 3-hydroxy-3-methylglutaryl-CoA. Metabolic flux through this bridge is increased either in the isovaleryl-CoA dehydrogenase null mutant or when the degradation of the ketogenic carbon sources is affected. We also observed a preference for fatty acids synthesis from ketogenic carbon sources, since blocking acetyl-CoA production from both glucose and threonine abolished acetate incorporation into sterols, while incorporation of acetate into fatty acids was increased. Interestingly, the growth of the isovaleryl-CoA dehydrogenase null mutant, but not that of the parental cells, is interrupted in the absence of ketogenic carbon sources, including lipids, which demonstrates the essential role of the mevalonate pathway. We concluded that procyclic trypanosomes have a strong preference for fatty acid versus sterol biosynthesis from ketogenic carbon sources, and as a consequence, that leucine is likely to be the main source, if not the only one, used by trypanosomes in the infected insect vector digestive tract to feed the mevalonate pathway.

The Interaction Mechanism of Intrinsically Disordered PP2A Inhibitor Proteins ARPP-16 and ARPP-19 With PP2A

Protein phosphatase 2A (PP2A) activity is critical for maintaining normal physiological cellular functions. PP2A is inhibited by endogenous inhibitor proteins in several pathological conditions including cancer. A PP2A inhibitor protein, ARPP-19, has recently been connected to several human cancer types. Accordingly, the knowledge about ARPP-19—PP2A inhibition mechanism is crucial for the understanding the disease development and the therapeutic targeting of ARPP-19—PP2A. Here, we show the first structural characterization of ARPP-19, and its splice variant ARPP-16 using NMR spectroscopy, and SAXS. The results reveal that both ARPP proteins are intrinsically disordered but contain transient secondary structure elements. The interaction mechanism of ARPP-16/19 with PP2A was investigated using microscale thermophoresis and NMR spectroscopy. Our results suggest that ARPP—PP2A A-subunit interaction is mediated by linear motif and has modest affinity whereas, the interaction of ARPPs with B56-subunit is weak and transient. Like many IDPs, ARPPs are promiscuous binders that transiently interact with PP2A A- and B56 subunits using multiple interaction motifs. In summary, our results provide a good starting point for future studies and development of therapeutics that block ARPP-PP2A interactions.

Interaction mechanism of endogenous PP2A inhibitor protein ENSA with PP2A

The vast diversity of protein phosphatase 2A (PP2A) holoenzyme composition ensures its multifaceted role in the regulation of cellular growth and signal transduction. In several pathological conditions, such as cancer, PP2A is inhibited by endogenous inhibitor proteins. Several PP2A inhibitor proteins have been identified, one of which is α-endosulfine (ENSA). ENSA inhibits PP2A activity when it is phosphorylated at Ser67 by Greatwall (Gwl) kinase. The role of ENSA in PP2A inhibition is rather well characterized, but knowledge of the mechanism of inhibition is scarce. In this study, we have performed comprehensive structural characterization of ENSA, and its interaction with PP2A A- and various B56-subunit isoforms by combining NMR spectroscopy, small-angle X-ray scattering (SAXS) and interaction assays. The results clearly indicate that ENSA is an intrinsically disordered protein containing three transient α-helical structures. ENSA was observed to interact PP2A mainly via A-subunit, as the affinity with the A-subunit is significantly stronger than with any of the B56 subunits. Based on our results, it seems that ENSA follows the dock-and-coalesce mechanism in associating with PP2A A-subunit. Taken together, our results provide an essential structural and molecular framework to understanding molecular bases of ENSA-mediated PP2A inhibition, which is crucial for the development of new therapies for diseases linked to PP2A inhibition.

Comparative study of esmolol and labetalol to attenuate haemodynamic responses after electroconvulsive therapy

OBJECTIVE

The study was designed to evaluate the hemodynamic effects of Esmolol and labetalol in patients undergoing electroconvulsive therapy.

MATERIALS AND METHODS

Ninety patients undergoing electroconvulsive therapy treatment were studied according to randomized, double blind placebo controlled protocol. Ninety patients were divided into three groups with thirty patients in each group. Patients received either Esmolol (1 mg/kg), Labetalol (0.25 mg/kg) or Normal Saline (placebo) intravenously just after induction with propofol. The baseline heart rate and blood pressure were recorded. Hemodynamic parameters before and after drug therapy and after the ECT current application, were recorded at different time intervals.

RESULTS

It was found that Esmolol significantly attenuated the degree of tachycardia and hypertension after ECT in comparison with placebo in the first three minutes (p<0.05), whereas the rise in HR and blood pressure was significantly blunted in the labetalol group in comparison to placebo, from three minutes onward till ten minutes. (p<0.05).

CONCLUSION

It was concluded that Esmolol is effective in blunting the hemodynamic response after ECT stimulus in the first three minutes after application of the electrical current, whereas Labetalol is effective after five minutes onwards till ten minutes.

Peripartum cardiomyopathy undergoing caesarean section under epidural anaesthesia

PURPOSE

To report a case of peripartum dilated cardiomyopathy presenting for emergency caesarean section, this was successfully managed with Epidural Anaesthesia.

CLINICAL FEATURES

A parturient suffering from idiopathic peripartum cardiomyopathy (E.F. 18%) was brought for an emergency caesarean section. Epidural anaesthesia was performed and 2% Lignocaine with adrenaline total 13 ml was injected into the epidural space. The patient's haemodynamic status was monitored with NIBP, ECG, pulse oximetry. Patient's perioperative course was uneventful.

CONCLUSION

In patients suffering from peripartum cardiomyopathy, undergoing caesarean section epidural anaesthesia is an acceptable anaesthetic alternative.

Chemical shift assignments of the catalytic domain of Staphylococcus aureus LytM

S. aureus resistance to antibiotics has increased rapidly. MRSA strains can simultaneously be resistant to many different classes of antibiotics, including the so-called "last-resort" drugs. Resistance complicates treatment, increases mortality and substantially increases the cost of treatment. The need for new drugs against (multi)resistant S. aureus is high. M23B family peptidoglycan hydrolases, enzymes that can kill S. aureus by cleaving glycine-glycine peptide bonds in S. aureus cell wall are attractive targets for drug development because of their binding specificity and lytic activity. M23B enzymes lysostaphin, LytU and LytM have closely similar catalytic domain structures. They however differ in their lytic activities, which can arise from non-conserved residues in the catalytic groove and surrounding loops or differences in dynamics. We report here the near complete 1H/13C/15N resonance assignment of the catalytic domain of LytM, residues 185-316. The chemical shift data allow comparative structural and functional studies between the enzymes and is essential for understanding how these hydrolases degrade the cell wall.

Comparative study between bupivacaine heavy vs pethidine intrathecally to study early haemodynamic changes and postoperative analgesia in patients undergoing caesarean section

OBJECTIVE

To study early hemodynamic changes and duration of postoperative analgesia between two study groups of intrathecal pethidine and bupivacaine heavy in patients undergoing caesarean section.

METHODOLOGY

Total number of 60 patients of ASA I and II, undergoing caesarean section were enrolled in the study. All the patients were divided into two groups: Pethidine and Bupivacaine heavy. The dose of pethidine for subarachnoid block was 1mg/kg and in Bupivacaine group 2.2 ml of 0.5% bupivacaine heavy was given intrathecally. Heart rate and blood pressure of all the patients were recorded before subarachnoid block. After giving spinal anesthesia, the heart rate and blood pressure were monitored and recorded in different time intervals. The duration of postoperative analgesia in all patients was recorded in postoperative ward. The APGAR Scores of the babies were recorded in 1 and 5 minutes after delivery. The data were statistically compared using independent sample t-test.

CONCLUSION

The hemodynamic parameters (HR & BP) were compared in different time intervals. The difference in heart rate and blood pressure at different time intervals in the two study groups were statistically insignificant as (p > 0.05). The total duration of postoperative analgesia in patients receiving sole intrathecal pethidine was 8 hours and 30 minutes. Where as, in Bupivacaine group the duration was 2 hrs and 36 minutes. This has been found statistically significant (p<0.05).

Effects of intrathecal fentanyl as an adjunct to hyperbaric bupivacaine in spinal anesthesia for elective caesarean section

Hyperbaric bupivacaine is the most common drug used in spinal anesthesia for caesarean section. The aim of this study was to compare the effects of adding fentanyl to intrathecal bupivacaine on the onset and duration of spinal anesthesia and its effect on mother and neonate. Seventy healthy parturients with singleton pregnancy scheduled for elective cesarean section were randomly allocated to receive subarachnoid block with 0.5% bupivacaine heavy 2.4 ml (Group A) or fentanyl 20 microgram (0.4 ml) added to 0.5% bupivacaine heavy 2 ml (Group B). Blood pressure, heart rate, respiratory rate, oxygen saturation, along with characteristics of spinal block were assessed throughout the surgery and in the postoperative ward until the patient requested for analgesia. It was found that duration of sensory block was prolonged in fentanyl group (p < 0.05). Duration of complete analgesia (97 ± 8.23 minutes vs 153 ± 7 minutes; p value = 0.00) and effective analgesia (134 ± 5.6 minutes vs 164 ± 9; p value = 0.00) were also found to be prolonged in Group B. There was not much difference in the occurrence of side effects in both the groups. Addition of fentanyl to intrathecal bupivacaine for cesarean section increases the duration of postoperative analgesia without increasing maternal or neonatal side effects.

Comparative study between tramadol and dexamethasone as an admixture to bupivacaine in supraclavicular brachial plexus block

This is a prospective, randomized, double blind study to evaluate the postoperative analgesia following supraclavicular brachial plexus block with Tramadol or Dexamethasone as an admixture to bupivacaine in upper extremity surgery. Total 60 patients of ASA I and II undergoing upper extremity surgery under brachial plexus block with Bupivacaine were randomly divided in to two groups; one group received Tramadol (2 mg/kg) and the other group received Dexamethasone (8 mg) as an admixture to Bupivacaine. The duration of postoperative analgesia was recorded in both groups using pain VAS score which was determined by maximum VAS score of 8-10 and when patient demands for additional analgesics. The mean duration of postoperative analgesia in the Dexamethasone group was 1028.00 minutes while in the tramadol group it was 453.17 minutes We concluded that Dexamethasone with local anaesthetic prolongs postoperative analgesia significantly than Tramadol (P<0.05) when used as admixture to local anaesthetic in brachial plexus block in upper extremity surgery.

Reassessing the substrate specificities of the major Staphylococcus aureus peptidoglycan hydrolases lysostaphin and LytM

Orchestrated action of peptidoglycan (PG) synthetases and hydrolases is vital for bacterial growth and viability. Although the function of several PG synthetases and hydrolases is well understood, the function, regulation, and mechanism of action of PG hydrolases characterised as lysostaphin-like endopeptidases have remained elusive. Many of these M23 family members can hydrolyse glycyl-glycine peptide bonds and show lytic activity against Staphylococcus aureus whose PG contains a pentaglycine bridge, but their exact substrate specificity and hydrolysed bonds are still vaguely determined. In this work, we have employed NMR spectroscopy to study both the substrate specificity and the bond cleavage of the bactericide lysostaphin and the S. aureus PG hydrolase LytM. Yet, we provide substrate-level evidence for the functional role of these enzymes. Indeed, our results show that the substrate specificities of these structurally highly homologous enzymes are similar, but unlike observed earlier both LytM and lysostaphin prefer the D-Ala-Gly cross-linked part of mature peptidoglycan. However, we show that while lysostaphin is genuinely a glycyl-glycine hydrolase, LytM can also act as a D-alanyl-glycine endopeptidase.