Total anomalous pulmonary venous connection: helical computed tomography as an alternative to angiography.

BACKGROUND: Echocardiographic evaluation of the pulmonary veins is inadequate at times. Cardiac catheterization, especially in sick neonates, may be a high-risk procedure. Helical computed tomography with three-dimensional reconstruction is noninvasive but remains an underutilized modality. METHODS AND RESULTS: Between January 2002 and February 2003, 7 computed tomography scans of children 3 weeks to 5 years of age were performed to evaluate the drainage of the pulmonary veins in suspected total anomalous venous drainage. Helical computed tomography (GE High speed Advantage) was performed using 2 mm sections, and rapid bolus hand injections of 2 ml/kg body-weight of nonionic intravenous contrast. Sagittal and coronal reformats, and three-dimensional reconstructions were performed, and reviewed by the radiologist. The findings were discussed with the pediatric cardiologist and surgeon involved in the case. The diagnoses included complex congenital heart disease (n = 5), isolated infradiaphragmatic total anomalous pulmonary venous connections (n = 1), and transposition of the great arteries with total anomalous pulmonary venous connections (n = 1). Cardiac computed tomography accurately demonstrated infradiaphragmatic total anomalous pulmonary venous connections in 4, and supracardiac drainage in 3 patients, in addition to the other cardiac findings. The findings on computed tomography scan correlated with surgical (n = 5) and/or angiographic findings (n = 2) in 7 patients. CONCLUSIONS: In sick, high-risk patients, cardiac computed tomography can be considered as an alternative to cardiac catheterization for the evaluation of pulmonary venous drainage.

Effect of support materials on cephamycin C production by immobilized Streptomyces clavuligerus.

In order to know the effect of supports on cephamycin C production, under similar experimental conditions, S. clavuligerus cells were immobilized with--sponge, 2% agar, 2% and 4% alginate support materials. An experimental set of free cell was also maintained as control. Cephamycin C production by these immobilized and free cells was estimated at 48, 96 and 120 hr of fermentation. In all the cases cephamycin C production was found to be high at 120 hr of fermentation. Sponge was found to be a better support material than other supports used for immobilization.

Development of indicators for cephamycin bioassay.

Several species of bacteria have been tested, for their sensitivity to cephamycin C and other beta-lactam antibiotics with a view to develop an indicator system for identification and quantitation of cephamycin. During the study, a mutant derived from E. coli K 802, exhibited a 10-fold increased sensitivity to cephamycin C than E. coli ESS (reference strain)1,2 and was designated as supersensitive E. coli K 8025. Another interesting feature observed during the investigation was that a strain of Serratia, showed a high degree of resistance to penicillins and cephalosporins however, it was sensitive to cephamycin and its derivative. It has been suggested that E. coli K 8025 and Serratia would serve as good indicator organisms for detection and quantitation of cephamycin.

Baculovirus vector-mediated expression of heterologous genes in insect cells.

The baculovirus expression system employing Autagrapha californica nuclear polyhidrosis virus and Spodoptera frugiperda insect cells in culture has proved very popular for high level expression of heterologous genes: In this system, transcription of the foreign gene is usually driven by the hyperactive and temporally regulated polyhedrin gene promoter. Replacement of the polyhedrin gene, which encodes a 29-kDa occlusion protein (non-essential for viral replication), with a gene of interest leads to an occlusion negative phenotype which serves as a visual marker to select for recombinant viruses. Simultaneous expression of multiple genes can also be achieved. The heterologous proteins synthesized in this system are antigenically, immunologically and functionally identical in most respects to their native counterparts. This mini-review will aim at summarizing the potentials and utility of the baculovirus expression vector system and will address some important questions relating to the biology of this system.

Over-expression and characterization of recombinant beta subunit of the human chorionic gonadotropin hormone synthesized in insect cells infected with a genetically engineered baculovirus.

A recombinant baculovirus, vAc beta hCG, having a replacement of the viral polyhedrin gene with the cDNA encoding the beta subunit of hCG was used to express beta hCG, an extensively glycosylated hormone, in insect cells. Virus-infected cells, 72 hr pi, secreted approximately 8.02 micrograms beta hCG/2 x 10(6) cells/ml. The recombinant beta hCG purified from insect cells exhibited increased mobility on SDS-PAGE as compared to authentic urinary beta hCG, a reflection on differences in glycosylation between insect and mammalian systems. The insect derived beta hCG, however, was identical to the native hormonal peptide in terms of immunoreactivity and bioactivity on association with alpha-subunit, as evident by its binding to rat testicular receptors and induction of steroidogenesis in a mouse Leydig cell bioassay system. The implications of using the baculovirus system to study the importance of carbohydrates for biological activity are also discussed.

Antimutagenic activity of plumbagin in Ames Salmonella typhimurium test.

This paper reports the antimutagenic activity of plumbagin (5-hydroxy-2-methyl-1, 4-naphthoquinone) against certain known chemical mutagens in a standard mutagenicity test system of Ames using S. typhimurium strains. Plumbagin by itself did not show any mutagenic effect, whereas it reduced significantly the mutagenic effect of 4-nitrophenylene diammine, phenyl hydrazine and sodium azide in test strains of S. typhimurium, suggesting that plumbagin possessed antimutagenic activity.

Construction, purification and characterization of a recombinant baculovirus containing the gene for alpha subunit of human chorionic gonadotropin.

A cDNA encoding the alpha subunit of human chorionic gonadotropin, a placental glycoprotein hormone, was cloned downstream to the viral polyhedrin gene promoter of Autographa california nuclear polyhedrosis virus and the recombinant transfer vector was used to co-transfect Spodoptera frugiperda cells growing in culture. Recombinant baculovirus carrying the alpha hCG gene was detected and isolated after dot hybridization using supernatant from co-transfected cells. Recombinant vAc alpha hCG having a replacement of the viral polyhedrin gene, which is hyper-transcribed very late in the infection cycle, with the alpha hCG cDNA was purified after a single round of plaque purification. Insect cell culture infected with vAc alpha hCG, secreted high levels of hCG which was biologically active.

Effects of plumbagin on antibiotic resistance in bacteria.

Plumbagin, a compound derived from the roots of Plumbago zeylanica (Chitramool) was studied for its effect on the development of antibiotic resistance using antibiotic sensitive strains of Escherichia coli and Staphylococcus aureus. A delayed growth was seen when these organisms were inoculated into the antibiotic (streptomycin/rifampicin) medium, due to development of resistance in some of the cells. However, the growth was completely prevented when the bacteria were grown in the medium containing antibiotic and plumbagin together, and this was attributed to prevention of development of antibiotic resistant cells.