Inherited cardiac arrhythmia syndromes: What have they taught us about arrhythmias and anti‐arrhythmic therapy?

1. In recent years, the identification of the gene defects in a vast array of monogenic disorders has revolutionized our understanding of the basic mechanisms underlying numerous disease processes. 2. Mutations in cardiac ion channels have been identified as the basis of a wide range of inherited arrhythmia syndromes, including the congenital long QT syndromes, Brugada syndrome, Lenegre syndrome, Andersen's disease and familial atrial fibrillation. 3. Identification of mutations in the human-ether-a-go-go-related gene (HERG) K(+) channel as the molecular basis of congenital long QT syndrome type 2 also led to the discovery that HERG is the molecular target for the vast majority of drugs (both cardiac and non-cardiac) that cause drug-induced arrhythmias. This has had profound implications not only for the development of anti-arrhythmic agents, but also for drug development in general. 4. The sequencing of the human genome in a sense represents the pinnacle of the reductionist era of molecular medicine. The great challenge now is to re-integrate the information gathered during the 'reductionist era' to provide a better understanding of the intact organism. Computer modelling is likely to be a key component of that re-integration process.     

Immune responses against Salmonella enterica serovar enteritidis infection in virally immunosuppressed chickens

To understand the role of immune mechanisms in protecting chickens from Salmonella infections, we examined the immune responses of Salmonella enterica serovar Enteritidis-infected chickens and the effect of chicken anemia virus (CAV), a T-cell-targeted virus, on S. enterica serovar Enteritidis-induced immune responses. One-day-old chicks were orally inoculated with S. enterica serovar Enteritidis with or without intramuscular injection of CAV. The bacterial infection, pathology, and immune responses of chickens were evaluated at 14, 28, and 56 days postinoculation. The infection increased the levels of S. enterica serovar Enteritidis-specific mucosal immunoglobulin A (IgA), the number of gut-associated T cells, and the titer of serum IgG specific for S. enterica serovar Enteritidis surface antigens. CAV infection depressed these immune responses, especially the mucosal immune responses, but did not increase the number of S. enterica serovar Enteritidis-infected cells in the intestine. The severity of pathological lesions appeared to be reciprocal to the level of immune responses, but the S. enterica serovar Enteritidis infection persisted. These results suggest that oral infection of S. enterica serovar Enteritidis in chickens induces both mucosal and systemic immune responses, which have a limited effect on the S. enterica serovar Enteritidis infection under conditions designed to mimic the field situation.     

X-ray powder diffraction patterns for certain fluoroquinolone antibiotic drugs

X-ray powder diffraction (XRD) data for six pure fluoroquinolone antibiotic drugs, ciprofloxacin, norfloxacin, enrofloxacin, ofloxacin, pefloxacin and sparfloxacin have been obtained using a powder diffractometer. The drugs were scanned from a Bragg angle (2theta) of 10 degrees to 70 degrees. The obtained data were tabulated in terms of the lattice spacing (A) and relative line intensities (I/I(I)). This new information may be useful for the identification of these drugs.     

The sensitivity of indicators of thrombosis initiation to a bileaflet prosthesis leakage stimulus

BACKGROUND AND AIM OF THE STUDY: The recent clinical history and experimental studies of the Medtronic Parallel (MP) valve suggest that bileaflet valve leakage flow is a primary initiator of thrombosis. These studies investigated the effects of physiologic leakage flow through a MP valve on various markers of blood damage. METHODS: A centrifugal pump was used to drive whole, human blood anticoagulated with PPACK through a circuit containing a MP 27 mm valve in the closed position (experimental runs) or a MP 27 mm valve in the open position (control runs). Samples were taken at set time intervals after the start of the pump. These samples were analyzed by cell counting, flow cytometry, and ELISA. RESULTS: Cell counts remained relatively constant in both the experimental and control runs. Increases in plasma hemoglobin concentration and the percentage of glycophorin A-positive fragments in the cell population were not significant in either the experimental or the control runs. Plasma platelet factor 4 activity and the percentage of the CD41-positive population which was positive for annexin V increased significantly (p <0.05) in the experimental runs compared with the control runs. CONCLUSION: The results indicate that bileaflet valve leakage flow causes significant platelet disruption, that erythrocytes are more resistant to disruption by leakage flow than platelets and granulocytes, and that annexin V binding to platelets and plasma platelet factor 4 activity are more sensitive markers of leakage induced blood damage than plasma hemoglobin concentration.     

Adrenal status in children with septic shock using low-dose stimulation test.

OBJECTIVES: There is paucity of data on the magnitude of absolute or relative adrenal insufficiency in septic shock, especially in children. We conducted a prospective study to determine the prevalence of adrenal insufficiency in children with septic shock using a low-dose Synacthen (1 microg) stimulation test. DESIGN: Cross-sectional study. SETTING: Pediatric intensive care unit in a tertiary care hospital in northern India. PATIENTS: Children with septic shock. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: We performed cortisol estimation at baseline and after low-dose Synacthen (1 microg) stimulation at 30 and 60 mins in children with fluid refractory septic shock admitted to our pediatric intensive care unit. Basal cortisol levels <7 microg/dL and peak cortisol level <18 microg/dL were used to define adrenal insufficiency. An increment of <9 microg/dL after stimulation was used to diagnose relative adrenal insufficiency. As there is lack of consensus on the cutoffs for defining relative adrenal insufficiency using the low-dose adrenocorticotropic hormone test, we evaluated different cutoff values (increment at 30 mins, increment at 60 mins, greater of the two increments) and evaluated their association with the incidence of catecholamine refractory shock and outcomes. Children with sepsis but without septic shock were sampled for baseline cortisol levels as a comparison. Thirty children (15 girls) with septic shock were included; median age (95% confidence interval) was 36.5 (9.39- 58.45) months. Median Pediatric Risk of Mortality score was 22.5 (14.13-24.87). Fifteen (50%) children survived. The median (95% confidence interval) cortisol values at baseline and 30 mins and 60 mins after stimulation were 71 (48.74-120.23) microg/dL, 78.1 (56.9-138.15) microg/dL, and 91 (56.17-166.44) microg/dL, respectively. The median baseline cortisol value in age- and gender-matched children with sepsis was 11.5 microg/dL. None of the children with septic shock fulfilled the criteria for absolute adrenal insufficiency. However, nine (30%) patients had relative adrenal insufficiency (increment in cortisol <9 microg/dL). Of these nine patients, five (56%) died; of the 21 patients with a greater increment in cortisol after stimulation, ten died (p = .69). Compared with patients in septic shock with normal adrenal reserve, those with relative adrenal insufficiency had a higher incidence of catecholamine refractory shock (p = .019) but no difference in mortality rate (p = .69). On the sensitivity and specificity analysis using various cutoffs of increment, the best discrimination for catecholamine refractory shock was obtained with a peak increment <6 microg/dL. CONCLUSIONS: Relative adrenal insufficiency is common in children with septic shock and is associated with catecholamine refractory shock.