Biomedical subjects

S Vestri

Publications and source records attributed to S Vestri.

4 recordsLinked to original sources

PubMed2001

Changes in sodium or glucose filtration rate modulate expression of glucose transporters in renal proximal tubular cells of rat.

Renal glucose reabsorption is mediated by luminal sodium-glucose cotransporters (SGLTs) and basolateral facilitative glucose transporters (GLUTs). The modulators of these transporters are not known, and their substrates glucose and Na+ are potential candidates. In this study we examined the role of glucose and Na+ filtration rate on gene expression of glucose transporters in renal proximal tubule. SGLT1, SGLT2, GLUT1 and GLUT2 mRNAs were assessed by Northern blotting; and GLUT1 and GLUT2 proteins were assessed by Western blotting. Renal cortex and medulla samples from control rats (C), diabetic rats (D) with glycosuria, and insulin-resistant 15-month old rats (I) without glycosuria; and from normal (NS), low (LS), and high (HS) Na+-diet fed rats were studied. Compared to C and I rats, D rats increased (P < 0.05) gene expression of SGLT2 by approximately 36%, SGLT1 by approximately 20%, and GLUT2 by approximately 100%, and reduced (P < 0.05) gene expression of GLUT1 by more than 50%. Compared to NS rats, HS rats increased (P < 0.05) SGLT2, GLUT2, and GLUT1 expression by approximately 100%, with no change in SGLT1 mRNA expression, and LS rats increased (P < 0.05) GLUT1 gene expression by approximately 150%, with no changes in other transporters. In summary, the results showed that changes in glucose or Na+ filtrated rate modulate the glucose transporters gene expression in epithelial cells of the renal proximal tubule.

Animals↗

PubMed1995

A chimeric saporin-transferrin conjugate compared to ricin toxin: role of the carrier in intracellular transport and toxicity.

Human transferrin (Tf) and saporin-6 (Sap), a ribosome inactivating protein from Saponaria officinalis, were chemically conjugated: the reaction generated two chimeras (called Tf-Sap) that proved to be cytotoxic to HepG2 cells. Electrophoretic and chromatographic analysis revealed that the two conjugates contained saporin and Tf in a 2:1 or 1:1 molar ratio (140 and 110 KDa, respectively). Free saporin is essentially nontoxic, whereas Tf-Sap efficiently kills HepG2 cells, although its ID50 (= 6 nM) is 1000-fold greater than that of ricin. Intracellular transport of these toxins was followed by in vivo fluorescence video microscopy, preparing the conjugates starting from rhodamine isothiocyanate-labeled saporin. Image analysis of living HepG2 cells exposed to fluorescent Tf-Sap revealed that the endocytotic pathway involving passage through secondary endosomes is dictated by Tf and is different from that of ricin (the dimeric toxin from Ricinus communis), which is delivered to the Golgi apparatus, the probable site of activation. We discuss whether differences in toxicity between ricin and Tf-Sap can be attributed to the different mechanisms of transport and activation.

Antineoplastic Agents, Phytogenic↗

PubMed1992

Confocal-line microscopy.

The confocal-line (CL) technique combines some of the characteristics of confocal-scanning microscopy with those of conventional-imaging methods. It is based on the introduction of line-shaped illumination and linear image detection, as an alternative to the current confocal-point (CP) approach. Although confocal only in one dimension, the proposed solution offers performance and features adequate to a variety of biological and non-biological applications and is also adaptable to an increased number of microscopical observations and measurements. The absence of moving components in the optical path and the use of electronic linear imagers permits flexible and fast operation that appears particularly relevant in many fields of basic and applied research. For instance, transmission, reflection and emission images can simultaneously be collected from the same area of the specimen, with slight adjustments to the optical setup. Useful extensions of CL microscopy to the field of spectral imaging are obtained with the introduction of a slit, a polychromator and an area detector, substituting for the linear imager. Prototype instrumentation has been constructed working from the cited principles and some tests have been performed on selected applications.

Autoradiography↗

PubMed1990

Mechanism of potassium transport across proximal tubule epithelium in the rat.

The mechanism of proximal tubule potassium reabsorption was studied by stopped-flow microperfusion and determination of potassium activities by ion-sensitive resin microelectrodes. The proximal tubule was unable to establish transepithelial potassium gradients. Perfusion with 20 mM K+ turned the lumen 3 mV more negative, an effect abolished by Ba2+. The half-time for K+ activities to reach their stationary level after perfusion with 1 mM K+ was significantly increased by Ba2+ from 4.25 +/- 0.14 s to 11.0 +/- 1.71 s, and after perfusion with 20 mM K+, from 5.43 +/- 0.20 to 12.53 +/- 0.90 s. These data indicate that a significant fraction of potassium is transferred across proximal tubule epithelium by a transcellular, K(+)-channel-dependent route.

Animals↗