Interaction of HIV-1 with susceptible lymphoblastoid cells. 1H NMR studies.

Different strains of HIV susceptible lymphoblastoid cells have been infected by HIV-1 and examined by means of 1H NMR spectroscopy at different times after infection, taking advantage of the presence of high resolution lipid signals from the plasma membrane of tumor cells. A transient decrease in intensity of fatty acid signals, originated by changes in membrane structure, has been observed early after viral infection. Marked alterations in membrane-dependent steps of phospholipid synthesis can also be inferred by the observed transient depression in peaks from choline-based metabolites. Spectral modifications deriving from changes in lipid metabolism are also produced both in infected cells a few days after infection and in permanently infected cells. 1H NMR can, therefore, monitor structural and metabolic effects induced by HIV infection.     

Role of percutaneous pelvic node aspiration cytology in the management of bladder carcinoma

Six of the 23 patients with bladder carcinoma who underwent percutaneous pelvic node aspiration biopsy cytology for staging purposes showed positive findings from nodal chains. Pelvic lymphadenectomy revealed no false-positive or false-negative cytologic results. The fine needle aspiration of opacified pelvic nodes under fluoroscopic control is of great diagnostic value, with a high accuracy in detecting nodal extension of bladder carcinoma and providing a rational basis for proper therapy. Positive aspiration results may be accepted as a basis for therapeutic decisions. Since the metastatic involvement of multiple nodes makes any therapeutic treatment as well as cystectomy completely useless, positive aspirations from more than two nodes may spare patients an unnecessary radical surgery.     

Pachytene analysis in a 17;21 reciprocal translocation carrier: role of the acrocentric chromosomes in male sterility

Summary Pachytene analysis was undertaken in an infertile male, heterozygous for a 17;21 reciprocal translocation. The quadrivalent was identified by its configuration and chromomere pattern. A non-random association was found between the quadrivalent and the sex vesicle in 77% of the pachytene nuclei analysed. In 13.1% of the cells the contact with the sex vesicle was established by the terminal chromomere of the two chromosomes 21; in 63.9% of the cells, the entire region of the breakpoints was completely hidden by the sex vesicle. In some nuclei asynapsis was found in the region of the breakpoints. The nature of the contact between the quadrivalent and the sex vesicle is discussed in this paper. It is proposed that the acrocentric chromosome favours the contact between the quadrivalent and the sex vesicle, and increases the risk of sterility in male carriers of Robertsonian translocations and of reciprocal translocations involving one acrocentric chromosome.     

Inhibition of the Na+/Ca2+ exchange in cardiac sarcolemmal vesicles by amiloride

The pyrazine diuretic amiloride inhibits the Na+/Ca2+ exchange activity of cardiac sarcolemmal vesicles in a concentration-dependent way. A good relationship between the uptake of amiloride by the vesicles and the inhibition of the exchanger has been found. Kinetic analyses indicate that the inhibition of Na+/Ca2+ exchange activity by amiloride is non-competitively removed by Ca2+ and competitively overcome by an outwardly directed Na+ gradient.     

Evaluation of neem seed powder for Fusarium wilt and Meloidogyne control on tomato

Fusarium wilt and root-knot are important diseases of tomato. The use of chemical is becoming less appealing because of the health implications. Also, the chemicals required are often not within the reach of farmers in most of the developing part of the world. This research is aimed at finding an alternative mode of control. Tomato variety Roma VF inoculated with Meloidogyne and Fusarium were treated with 2 g/kg soil neem seed powder in the screenhouse and 2 Mg ha ^{? 1} in the field. An untreated and Furadan treated plot in the field served as control. Neem seed powder significantly reduced the disease severity of Fusarium and root-knot in both screenhouse and field. Results suggest the possible use of neem seed powder for control of the root-knot nematodes - Fusarium wilt disease complex.     

Testing statistical significance scores of sequence comparison methods with structure similarity

Background  

In the past years the Smith-Waterman sequence comparison algorithm has gained popularity due to improved implementations and rapidly increasing computing power. However, the quality and sensitivity of a database search is not only determined by the algorithm but also by the statistical significance testing for an alignment. The e-value is the most commonly used statistical validation method for sequence database searching. The CluSTr database and the Protein World database have been created using an alternative statistical significance test: a Z-score based on Monte-Carlo statistics. Several papers have described the superiority of the Z-score as compared to the e-value, using simulated data. We were interested if this could be validated when applied to existing, evolutionary related protein sequences.     

A necrotic cell death model in a protist

While necrotic cell death is attracting considerable interest, its molecular bases are still poorly understood. Investigations in simple biological models, taken for instance outside the animal kingdom, may benefit from less interference from other cell death mechanisms and from better experimental accessibility, while providing phylogenetic information. Can necrotic cell death occur outside the animal kingdom? In the protist Dictyostelium, developmental stimuli induced in an autophagy mutant a stereotyped sequence of events characteristic of necrotic cell death. This sequence included swift mitochondrial uncoupling with mitochondrial 2',7'-dichlorofluorescein diacetate fluorescence, ATP depletion and increased oxygen consumption. This was followed by perinuclear clustering of dilated mitochondria. Rapid plasma membrane rupture then occurred, which was evidenced by time-lapse videos and quantified by FACS. Of additional interest, developmental stimuli and classical mitochondrial uncouplers triggered a similar sequence of events, and exogenous glucose delayed plasma membrane rupture in a nonglycolytic manner. The occurrence of necrotic cell death in the protist Dictyostelium (1) provides a very favorable model for further study of this type of cell death, and (2) strongly suggests that the mechanism underlying necrotic cell death was present in an ancestor common to the Amoebozoa protists and to animals and has been conserved in evolution.