Effect of muscle relaxants on heart rate, arterial pressure, intubation conditions and onset of neuromuscular block in patients undergoing valve surgery

Sixty six patients undergoing elective valve surgery were randomized to receive rocuronium bromide 0.6 mg/Kg (Group R, n=22), pancuronium bromide 0.1 mg/Kg (Group P, n= 22) and vecuronium bromide 0.1 mg/Kg (Group V, n=22), Measurements of heart rate and arterial pressure (systolic, diastolic and mean) were noted at the following stages: 1) baseline when haemodynamics were stable for 2 minutes after induction of anaesthesia (2) one, (3) three, (4) five minutes after administration of muscle relaxants, (5) One, (6) three, and (7) five minutes after intubation. In group R, the heart rate decreased 5 min after injection of muscle relaxant from 93.9 +/- 21.3 to 82.4 +/- 20.7 beats/min (p<0.001). However, it increased to 128.3 +/- 25.8 beats/min (p<0.001) following intubation and returned to baseline at 5 min after intubation. In group P, heart rate increased from 98.8 +/- 32.6 to 109.6 +/- 32.7 beats/min (p<0.001), 1 min after injection of pancuronium and this increase persisted throughout the study period. In group V, heart rate decreased from 99.9 +/- 22.3 to 83.8 +/-19.6 beats/min (p<0.001) at 5 min after injection of the drug. It increased to 118.6 +/- 22.4 beats/min (p<0.001), 1 min after intubation and returned to baseline at 5 min after intubation. The decrease in heart rate in group R and V was accompanied by a significant decrease in systolic, diastolic and mean arterial pressure. In group P, only the systolic pressure decreased significantly at 5 min after injection of the drug. Intubation was accompanied by a significant increased in systolic, diastolic and mean arterial pressure in all the groups. Excellent intubation conditions (intubation score 3-4) were observed with all the three drugs, however, there were number of patients in group P who showed diaphragmatic movement during intubation. Onset of action of muscle relaxant, was fastest with rocuronium (group R=132.7 +/- 0.3 sec, P=182.6 +/- 68.5 sec, V= 144.8 +/- 46.1 sec, Group P vs Group R). To conclude, pancuronium causes significant increase in heart rate and should be preferred in patients with regurgitant lesions having slower baseline heart rate. Vecuronium and rocuronium decrease the heart rate and should be preferred in patient with faster baseline heart rate. In terms of intubating conditions rocuronium and vecuronium provide best conditions, but onset is faster with rocuronium.     

Clinical and biochemical description of a novel CYP21A2 gene mutation 962_963insA using a new 3D model for the P450c21 protein

OBJECTIVE: A severely virilized 46, XX newborn girl was referred to our center for evaluation and treatment of congenital adrenal hyperplasia (CAH) because of highly elevated 17alpha-hydroxyprogesterone levels at newborn screening; biochemical tests confirmed the diagnosis of salt-wasting CAH. Genetic analysis revealed that the girl was compound heterozygote for a previously reported Q318X mutation in exon 8 and a novel insertion of an adenine between nucleotides 962 and 963 in exon 4 of the CYP21A2 gene. This 962_963insA mutation created a frameshift leading to a stop codon at amino acid 161 of the P450c21 protein. AIM AND METHODS: To better understand structure-function relationships of mutant P450c21 proteins, we performed multiple sequence alignments of P450c21 with three mammalian P450s (P450 2C8, 2C9 and 2B4) with known structures as well as with human P450c17. Comparative molecular modeling of human P450c21 was then performed by MODELLER using the X-ray crystal structure of rabbit P450 2B4 as a template. RESULTS: The new three dimensional model of human P450c21 and the sequence alignment were found to be helpful in predicting the role of various amino acids in P450c21, especially those involved in heme binding and interaction with P450 oxidoreductase, the obligate electron donor. CONCLUSION: Our model will help in analyzing the genotype-phenotype relationship of P450c21 mutations which have not been tested for their functional activity in an in vitro assay.     

Diastolic dysfunction after coronary artery bypass grafting--the effect of glucose-insulin-potassium infusion

BACKGROUND: Glucose-insulin-potassium (GIK) infusion improves clinical outcome after coronary artery bypass surgery (CABG). The mechanism of benefit is unclear, but GIK limits ischemia and reperfusion injury. This study was designed to assess whether the clinical benefit of perioperative GIK infusion is mediated through reduction in the severity of diastolic dysfunction that occurs after CABG. METHODS AND RESULTS: Thirty-one patients undergoing CABG were randomized to GIK infusion (n = 14) or no-GIK (n = 17). Left ventricular compliance, using pressure-area relationships, was assessed by simultaneous transesophageal echocardiographic measurement of LV end-diastolic area (LVEDA) and pulmonary capillary wedge pressure (PCWP) at baseline prior to CABG, early post cardiopulmonary bypass (CPB), after sternal closure, and 3 hours postoperatively. Measures of LVEDA were made at a constant PCWP and a decrease in LVEDA reflects a leftward shift in the pressure-area relationship consistent with decreased compliance. Both study groups demonstrated progressive and consistent worsening of LV compliance, as evidenced by a reduction of LVEDA from 17.0 +/- 3.9 cm(2) at baseline to 15.3 +/- 3.6 cm(2) after CPB, 14.6 +/- 2.9 cm(2) after sternal closure, and 14.1 +/- 3.2 cm(2) (p < 0.0001) at three hours postoperatively. LVEDA decreased from a baseline of 16.3 +/- 2.8 to 13.8 +/- 2.9 cm(2) in the GIK group, while the non-GIK group demonstrated a reduction of LVEDA from 17.5 +/- 4.6 to 14.3 +/- 3.5 cm(2). Doppler transmitral E wave deceleration time shortened as well, which is consistent with more restrictive LV filling due to rapid equilibration of LA and LV pressures. GIK infusion did not alter either measure of diastolic function significantly. CONCLUSION: Diastolic dysfunction occurs nearly universally after CABG, worsens with chest closure, persists for up to 3 hours postoperatively, and is unaffected by GIK. Despite theoretical reasons why GIK might limit ischemia and reperfusion injury, the clinical benefits do not appear to be related to amelioration of diastolic dysfunction. Support: The study was partially supported by Agilent Technologies/Philips Imaging.     

Protective effects of NIM811 in transient focal cerebral ischemia suggest involvement of the mitochondrial permeability transition

Cerebral ischemia followed by reperfusion activates numerous pathways that lead to cell death. One such pathway involves the release of large quantities of the excitatory amino acid glutamate into the synapse and activation of N-methyl-D-aspartate receptors. This causes an increase in mitochondrial calcium levels ([Ca(2+)](m)) and a production of reactive oxygen species (ROS), both of which may induce the mitochondrial permeability transition (MPT). As a consequence, there is eventual mitochondrial failure culminating in either apoptotic or necrotic cell death. Thus, agents that inhibit MPT might prove useful as therapeutic interventions in cerebral ischemia. In this study, we have investigated the neuroprotective efficacy of the novel compound NIM811. Similar in structure of its parent compound cyclosporin A, NIM811 is a potent inhibitor of the MPT. Unlike cyclosporin A, however, it is essentially void of immunosuppressive actions, allowing the role of MPT to be clarified in ischemia/reperfusion injury. The results of these studies demonstrate that NIM811 provides almost 40% protection in a model of transient focal cerebral ischemia. This was associated with a nearly 10% reduction in mitochondrial reactive species formation and 34% and 38% reduction of cytochrome c release in core and penumbra, respectively. Treatment with NIM811 also increased calcium retention capacity by approximately 20%. Interestingly, NIM811 failed to improve ischemia-induced impairment of bioenergetics. The neuroprotective effects of NIM811 were not due to drug-induced alterations in cerebral perfusion after ischemia. Activation of MPT appears to be an important process in ischemia/reperfusion injury and may be a therapeutic target.     

Posttraumatic stress symptom severity predicts marijuana use coping motives among traumatic event-exposed marijuana users

The present study examines the relation between posttraumatic stress symptom severity and motives for marijuana use among 103 (55 women) young adult marijuana users (current) who reported experiencing at least one traumatic event in their lifetime. As expected, after covarying for the theoretically relevant variables of frequency of past 30-day marijuana use, number of cigarettes smoked per day, and volume of alcohol consumed, posttraumatic stress symptom severity was significantly related to marijuana use coping motives, but no other motives for marijuana use. Results are discussed in relation to better understanding the role of coping-motivated marijuana use among young adults experiencing posttraumatic stress.     

Age affects outcomes in chronic kidney disease

Chronic kidney disease (CKD) is common among the elderly. However, little is known about how the clinical implications of CKD vary with age. We examined the age-specific incidence of death, treated end-stage renal disease (ESRD), and change in estimated glomerular filtration rate (eGFR) among 209,622 US veterans with CKD stages 3 to 5 followed for a mean of 3.2 years. Patients aged 75 years or older at baseline comprised 47% of the overall cohort and accounted for 28% of the 9227 cases of ESRD that occurred during follow-up. Among patients of all ages, rates of both death and ESRD were inversely related to eGFR at baseline. However, among those with comparable levels of eGFR, older patients had higher rates of death and lower rates of ESRD than younger patients. Consequently, the level of eGFR below which the risk of ESRD exceeded the risk of death varied by age, ranging from 45 ml/min per 1.73 m(2) for 18 to 44 year old patients to 15 ml/min per 1.73 m(2) for 65 to 84 year old patients. Among those 85 years or older, the risk of death always exceeded the risk of ESRD in this cohort. Among patients with eGFR levels <45 ml/min per 1.73 m(2) at baseline, older patients were less likely than their younger counterparts to experience an annual decline in eGFR of >3 ml/min per 1.73 m(2). In conclusion, age is a major effect modifier among patients with an eGFR of <60 ml/min per 1.73 m(2), challenging us to move beyond a uniform stage-based approach to managing CKD.     

NADPH-dependent covalent binding of [3H]paroxetine to human liver microsomes and S-9 fractions: identification of an electrophilic quinone metabolite of paroxetine

The primary pathway of clearance of the methylenedioxyphenyl-containing compound and selective serotonin reuptake inhibitor paroxetine in humans involves P450 2D6-mediated demethylenation to a catechol intermediate. The process of demethylenation also results in the mechanism-based inactivation of the P450 isozyme. While the link between P450 2D6 inactivation and pharmacokinetic interactions of paroxetine with P450 2D6 substrates has been firmly established, there is a disconnect in terms of paroxetine's excellent safety record despite the potential for bioactivation. In the present study, we have systematically assessed the NADPH-dependent covalent binding of [(3)H]paroxetine to human liver microsomes and S-9 preparations in the absence and presence of cofactors of the various phase II drug-metabolizing enzymes involved in the downstream metabolism/detoxification of the putative paroxetine-catechol intermediate. Incubation of [(3)H]paroxetine with human liver microsomes and S-9 preparations resulted in irreversible binding of radioactive material to macromolecules by a process that was NADPH-dependent. The addition of reduced glutathione (GSH) to the microsomal and S-9 incubations resulted in a dramatic reduction of covalent binding. Following incubations with NADPH- and GSH-supplemented human liver microsomes and S-9, three sulfydryl conjugates with MH(+) ions at 623 Da (GS1), 779 Da (GS2), and 928 Da (GS3), respectively, were detected by LC-MS/MS. The collision-induced dissociation spectra allowed an insight into the structure of the GSH conjugates, based on which, bioactivation pathways were proposed. The formation of GS 1 was consistent with Michael addition of GSH to the quinone derived from two-electron oxidation of paroxetine-catechol. GS 3 was formed by the addition of a second molecule of GSH to the quinone species obtained via the two-electron oxidation of GS 1. The mechanism of formation of GS 2 can be rationalized via (i) further two-electron oxidation of the catechol motif in GS 3 to the ortho-quinone, (ii) loss of a glutamic acid residue from one of the adducted GSH molecules, and (iii) condensation of a cysteine-NH 2 with an adjacent carbonyl of the ortho-quinone to yield an ortho-benzoquinoneimine structure. Inclusion of the catechol-O-methyltransferase cofactor S-adenosylmethionine (SAM) in S-9 incubations also dramatically reduced the covalent binding of [(3)H]paroxetine, a finding that was consistent with O-methylation of the paroxetine-catechol metabolite to the corresponding guaiacol regioisomers in S-9 incubations. While the NADPH-dependent covalent binding was attenuated by GSH and SAM, these reagents did not alter paroxetine's ability to inactivate P450 2D6, suggesting that the reactive intermediate responsible for P450 inactivation did not leave the active site to react with other proteins. The results of our studies indicate that in addition to the low once-a-day dosing regimen (20 mg) of paroxetine, efficient scavenging of the catechol and quinone metabolites by SAM and GSH, respectively, serves as an explanation for the excellent safety record of paroxetine despite the fact that it undergoes bioactivation.     

M-cell targeted biodegradable PLGA nanoparticles for oral immunization against hepatitis B

The transcytotic capability and expression of distinct carbohydrate receptors on the intestinal M-cells render it a potential portal for the targeted oral vaccine delivery. PLGA nanoparticles loaded with HBsAg were developed and antigen was stabilized by co-encapsulation of trehalose and Mg(OH)(2). Additionally, Ulex europaeus 1 (UEA-1) lectin was anchored to the nanoparticles to target them to M-cells of the peye's patches. The developed systems was characterized for shape, size, polydispersity index and loading efficiency. Bovine submaxillary mucin (BSM) was used as a biological model for the in vitro determination of lectin activity and specificity. The targeting potential of the lectinized nanoparticles were determined by Confocal Laser Scanning Microscopy (CLSM) using dual staining technique. The immune stimulating potential was determined by measuring the anti-HBsAg titre in the serum of Balb/c mice orally immunized with various lectinized formulations and immune response was compared with the alum-HBsAg given intramuscularly. Induction of the mucosal immunity was assessed by estimating secretary IgA (sIgA) level in the salivary, intestinal and vaginal secretion. Additionally, cytokines (interleukin-2; IL-2 and interferon-gamma; IFN-gamma) level in the spleen homogenates was also determined. The results suggest that HBsAg can be successfully stabilized by co-encapsulation of protein stabilizers. The lectinized nanoparticles have demonstrated approximately 4-fold increase in the degree of interaction with the BSM as compared to plain nanoparticles and sugar specificity of the lectinized nanoparticles was also maintained. CLSM showed that lectinized nanoparticles were predominantly associated to M-cells. The serum anti-HBsAg titre obtained after oral immunization with HBsAg loaded stabilized lectinized nanoparticles was comparable with the titre recorded after alum-HBsAg given intramuscularly. The stabilized UEA-1 coupled nanopartilces exhibited enhanced immune response as compared to stabilized non-lectinized nanoparticles. Furthermore, the stabilized lectinized nanoparticles elicited sIgA in the mucosal secretion and IL-2 and IFN-gamma in the spleen homogenates. These stabilized lectinized nanoparticles could be a promising carrier-adjuvant for the targeted oral-mucosal immunization.