Occurrence of "J waves" in 12-lead ECG as a marker of acute ischemia and their cellular basis

The "J wave" (also referred to as "the Osborn wave,""the J deflection," or "the camel's hump") is a distinctive deflection occurring at the QRS-ST junction. In 1953, Dr. John Osborn described the "J wave" as an "injury current" resulting in ventricular fibrillation during experimental hypothermia. Although "J Wave" is supposed to be pathognomonic of hypothermia, it is seen in a host of other conditions such as hypercalcemia, brain injury, subarachnoid hemorrhage, cardiopulmonary arrest from over sedation, the Brugada syndrome, vasospastic angina, and idiopathic ventricular fibrillation. However, there is paucity of literature data as regards to ischemic etiology of "J Wave." In this article, we present a case where "J waves" were probably induced by ischemia. We also discuss the mechanism of ischemia-induced "J wave" accentuation and its prognostic implications.

Pulmonary hypertension in isolated secundum atrial septal defect: high frequency in young patients

Out of 709 consecutive patients with isolated secundum atrial septal defect, the pulmonary artery systolic pressure was greater than 50 mm Hg in 118 patients (17%). Pulmonary hypertension was present in 13% of patients under 10 years and in 14% aged 11 to 20 years. The Eisenmenger reaction was present in 9% of the 709 patients. The frequency of the Eisenmenger reaction was high in young patients and was not significantly different in patients in the first and second decades as compared to older patients. None of our patients with pulmonary hypertension resided at high altitude. The high frequency of pulmonary hypertension in our young patients cannot be satisfactorily explained. Autopsy studies suggest that in some, pulmonary hypertension is due to the persistence of the fetal pulmonary vascular pattern.

Purification and characterization of recombinant Streptomyces clavuligerus isopenicillin N synthase produced in Escherichia coli

Recombinant isopenicillin N synthase from Streptomyces clavuligerus was produced in the form of inactive inclusion bodies in Escherichia coli. These inclusion bodies were solubilized by treatment with 5 M urea under reducing conditions. Optimization of refolding conditions to recover active isopenicillin N synthase indicated that a dialysis procedure carried out at a protein concentration of about 1.0 mg ml(-1) gave maximal recovery of active isopenicillin N synthase. Solubilized isopenicillin N synthase of more than 95% purity was obtained by passing this material through a DEAE-Trisacryl ion exchange column. Expression studies conducted at different temperatures indicated that isopenicillin N synthase was produced predominantly in a soluble, active form when expression was conducted at 20 degrees C, and accounted for about 20% of the total soluble protein. This high-level production facilitated the purification of soluble isopenicillin N synthase to near homogeneity in four steps. Characterization of the purified soluble and solubilized isopenicillin N synthase revealed that they are very similar.

Genetic and biochemical analysis of the cysteinyl residues of isopenicillin N synthase from Streptomyces clavuligerus

Isopenicillin N synthase (IPNS) from Streptomyces clavuligerus catalyses the oxidative cyclization of the acyclic tripeptide delta-(L-alpha-aminoadipyl)-L-cysteinyl-D-valine into isopenicillin N. All four of the cysteine residues found in this enzyme were mutated individually into serine residues, either by the polymerase chain reaction or by single-strand site-directed mutagenesis. Functional analysis of these single mutants showed that the C104S mutant lost more than 96% of its activity, while the remaining C37S, C142S, and C251S mutants each lost 30-50% of their activity. Treatment with the thiol-group-specific reagent N-ethylmaleimide confirmed the importance of the cysteine 104 residue. Activity analysis of an IPNS triple mutant (C37S, C142S, and C251S), prepared by recombining fragments of the IPNS-encoding pcbC gene from each of the three single mutants, showed that it had lost more than 90% of its activity. Conformational analysis by circular dichroism spectroscopy indicated that the IPNS triple mutant was structurally different from the wild type, suggesting that the loss of activity may be due to conformational changes rather than active site modifications.

High-level expression of the Streptomyces clavuligerus isopenicillin N synthase gene in Escherichia coli

The pcbC gene, which encodes isopenicillin N synthase (IPNS), was subcloned from Streptomyces clavuligerus into Escherichia coli by using the pT7 series of plasmid vectors. The polymerase chain reaction was used to introduce an NdeI site at the translation initiation codon of pcbC, allowing the gene to be inserted behind an E. coli type of ribosome binding site. This construction directed high-level expression of IPNS, but the IPNS was in an inactive form in inclusion bodies. Active IPNS was recovered by solubilizing and renaturing the protein.

Middle hepatic vein reconstruction in adult living donor liver transplantation: a randomized clinical trial

BACKGROUND

In adult right lobe living donor liver transplantation (LDLT), venous drainage of the anterior sector is usually reconstructed on the bench to form a neo-middle hepatic vein (MHV). Reconstruction of the MHV for drainage of the anterior sector is crucial for optimal graft function. The conduits used for reconstruction include cryopreserved allografts, synthetic grafts, or the recipient portal vein. However, the ideal choice remains a matter of debate. This study compares the efficacy of the native recipient portal vein (RPV) with PTFE grafts for reconstruction of the neo-MHV.

METHODS

Patients in this equivalence-controlled, parallel-group trial were randomized to either RPV (62 patients) or PTFE (60 patients) for use in the reconstruction of the neo-MHV. Primary endpoint was neo-MHV patency at 14 days and 90 days. Secondary outcomes included 90-day mortality and post-transplant parameters as scored by predefined scoring systems.

RESULTS

There was no statistically significant difference in the incidence of neo-MHV thrombosis at 14 days (RPV 6.5 per cent versus PTFE 10 per cent; P = 0.701) and 90 days (RPV 14.5 per cent versus PTFE 18.3 per cent; P = 0.745) between the two groups. Irrespective of the type of graft used for reconstruction, 90-day all-cause and sepsis-specific mortality was significantly higher among patients who developed neo-MHV thrombosis. Neo-MHV thrombosis and sepsis were identified as risk factors for mortality on Cox proportional hazards analysis. No harms or unintended side effects were observed in either group.

CONCLUSION

In adult LDLT using modified right lobe graft, use of either PTFE or RPV for neo-MHV reconstruction resulted in similar early patency rates. Irrespective of the type of conduit used for reconstruction, neo-MHV thrombosis is a significant risk factor for mortality.

REGISTRATION NUMBER

CTRI/2018/11/016315 (www.ctri.nic.in).