Biomedical subjects

J Pizzonia

Publications and source records attributed to J Pizzonia.

4 recordsLinked to original sources

PubMed2001

Electrophoresis gel image processing and analysis using the KODAK 1D software.

The present article reports on the performance of the KODAK 1D Image Analysis Software for the acquisition of information from electrophoresis experiments and highlights the utility of several mathematical functions for subsequent image processing, analysis, and presentation. Digital images of Coomassie-stained polyacrylamide protein gels containing molecular weight standards and ethidium bromide stained agarose gels containing DNA mass standards are acquired using the KODAK Electrophoresis Documentation and Analysis System 290 (EDAS 290). The KODAK 1D software is used to optimize lane and band identification using features such as isomolecular weight lines. Mathematical functions for mass standard representation are presented, and two methods for estimation of unknown band mass are compared. Given the progressive transition of electrophoresis data acquisition and daily reporting in peer-reviewed journals to digital formats ranging from 8-bit systems such as EDAS 290 to more expensive 16-bit systems, the utility of algorithms such as Gaussian modeling, which can correct geometric aberrations such as clipping due to signal saturation common at lower bit depth levels, is discussed. Finally, image-processing tools that can facilitate image preparation for presentation are demonstrated.

Algorithms↗

PubMed2000

Effects of cell volume fraction changes on apparent diffusion in human cells.

Diffusion-weighted imaging was used to study the relationship between apparent diffusion coefficient (ADC) and cell volume fraction in cell suspensions and packed arrays. Cell volume fraction was varied by changing extracellular fluid osmolarity (for human glial cells) and by changing cell density (for human glial and red blood cells). In packed arrays of glial cells, ADC increased 10% when cells shrank and decreased 13% when cells swelled. ADC decreased 34% as cell density increased from 0 to 72%. In erythrocyte suspensions, ADC decreased 90% as the cell density increased from 0 to 89%. These results agree with theoretical predictions.

Adult↗

PubMed1997

Sodium-hydrogen exchange isoform expression in blood cells: implications for studies in diabetes mellitus.

There have been many reports of increased Na-H exchange (NHE) activity in the peripheral blood cells (erythrocytes, lymphocytes and platelets) of patients with diabetes mellitus compared to nondiabetic controls. This raised NHE activity has been hypothesized to reflect increased NHE activity in kidney and vascular smooth muscle. Raised NHE activity in these tissues could play a pathophysiological role in mediating hypertension, vascular smooth muscle cell proliferation and progressive renal impairment. It is now known that there are at least five NHE isoforms, but a specific study examining expression of NHE isoforms in peripheral blood cells has not been reported. This study used specific antisera to NHE isoforms 1, 3 and 4 to examine NHE expression by immunoblot analysis. Erythrocyte, lymphocyte and platelet membranes from both rabbit and rat were separated by standard methods. A monoclonal antibody to NHE-1 reacted with a 100-110 kDa band in rabbit and rat platelets and lymphocytes (identical to that observed in basolateral-enriched renal cortical vesicles) and a 100 kDa band in rabbit and rat erythrocytes. In both species, the intensity of the staining was greatest in platelet membranes. A polyclonal antibody to NHE-3, the isoform present on the apical membranes of renal proximal tubule, showed no evidence of staining in any of the peripheral blood cell preparations. Similarly there was no evidence of expression of NHE-4 in the peripheral blood cell preparations. Peripheral blood cells express NHE-1, which likely accounts for amiloride-sensitive Na-H exchange in these cells, playing a role in cell volume and pH regulation. However, there is no evidence that there is expression of NHE-3 or NHE-4 in peripheral blood cells. These data have implications for studies in hypertension and diabetes mellitus which measure peripheral blood cell Na-H exchange and hypothesize regarding a direct pathophysiological role for this increased activity.

Animals↗

PubMed1993

NHE3: a Na+/H+ exchanger isoform of renal brush border.

Na+/H+ exchangers in the brush-border (luminal, apical) membrane of renal proximal tubules are responsible for active, transcellular reabsorption of NaHCO3 and NaCl. Although well characterized kinetically, the protein that mediates Na+/H+ exchange in the renal brush border has not been identified. Several Na+/H+ exchanger genes, including NHE1, NHE2, NHE3, and NHE4, are expressed in the kidney. To identify the NHE3 gene product and to determine its cellular and subcellular localization in the rabbit kidney, an NHE3-isoform-specific antibody was prepared. Guinea pigs were immunized with purified fusion protein containing the carboxy-terminal 40 amino acids of NHE3 (fpNHE3-C40). After affinity purification, immune sera demonstrated specific reactivity to the NHE3 sequence within the fusion protein as well as to an 80-kDa polypeptide expressed in NHE3-transfected LAP1 cells. Western blot analysis showed that anti-fpNHE3-C40 specifically reacted with an 80-kDa protein that is relatively enriched in renal brush-border membrane compared with basolateral membrane. Immunocytochemical studies confirmed that the Na+/H+ exchanger isoform NHE3 is expressed along the microvillar membrane of the brush border of proximal tubule cells in the rabbit kidney.

Animals↗