Biomedical subjects

J Dørup

Publications and source records attributed to J Dørup.

24 records · Page 2Linked to original sources

PubMedDate not supplied

Ultrastructure of distal nephron cells in rat renal cortex.

Distal nephron segments in the rat renal cortex contain distal convoluted tubule cells (DCT cells), connecting tubule cells (CNT cells), intercalated cells (I cells), and principal cells (P cells). The present study was carried out to expand present knowledge on the ultrastructure of these cells. The cells were sampled from superficial cortex and analyzed by electron microscopy. Several morphometric parameters were determined and statistical comparison between cell types was performed. Significant structural differences between the cell types were demonstrated. DCT cells showed the highest volume density of mitochondria whereas the amplification of basolateral membranes was higher in CNT cells than in I and P cells. The surface density of the membrane that bounds intermediate vesicles in the apical cytoplasm was twofold higher in I cells than in the other cell types. The morphological differentiation found in the present study adds to available evidence indicating a functional differentiation between the cell types and provides a reference for structure-function correlations in these cells.

Animals↗

PubMedDate not supplied

Structural adaptation of intercalated cells in rat renal cortex to acute metabolic acidosis and alkalosis.

The structural responses of cells in the distal convoluted, connecting, and collecting tubule to acute acid/base changes were investigated by electron microscopy. Acute metabolic acidosis was induced by administration of ammonium chloride, and acute metabolic alkalosis by potassium or sodium bicarbonate. Morphometric analyses were performed on micrographs of randomly selected distal nephron cells. No structural responses were found in distal convoluted tubule cells, connecting tubule cells, or principal cells but prominent changes were observed in intercalated cells (I cells). Thus, the surface density of the luminal membrane in I cells was significantly higher in acidotic animals and lower in KHCO3 alkalotic animals than in controls. On the contrary, the surface density of the membrane that bounds apical vesicles was higher in KHCO3 alkalotic and lower in acidotic animals than in controls. These results suggest that the luminal membrane is internalized during alkalosis and that the membrane that bounds apical vesicles is transferred to the luminal membrane during acidosis. Since a proton translocating ATPase may be present in the luminal membrane the observations are consistent with the possibility that cortical I cells participate in the maintenance of acid/base homeostasis.

Acidosis↗

PubMedDate not supplied

Wireless access to a pharmaceutical database: a demonstrator for data driven Wireless Application Protocol (WAP) applications in medical information processing.

BACKGROUND: The Wireless Application Protocol technology implemented in newer mobile phones has built-in facilities for handling much of the information processing needed in clinical work. OBJECTIVES: To test a practical approach we ported a relational database of the Danish pharmaceutical catalogue to Wireless Application Protocol using open source freeware at all steps. METHODS: We used Apache 1.3 web software on a Linux server. Data containing the Danish pharmaceutical catalogue were imported from an ASCII file into a MySQL 3.22.32 database using a Practical Extraction and Report Language script for easy update of the database. Data were distributed in 35 interrelated tables. Each pharmaceutical brand name was given its own card with links to general information about the drug, active substances, contraindications etc. Access was available through 1) browsing therapeutic groups and 2) searching for a brand name. The database interface was programmed in the server-side scripting language PHP3. RESULTS: A free, open source Wireless Application Protocol gateway to a pharmaceutical catalogue was established to allow dial-in access independent of commercial Wireless Application Protocol service providers. The application was tested on the Nokia 7110 and Ericsson R320s cellular phones. CONCLUSIONS: We have demonstrated that Wireless Application Protocol-based access to a dynamic clinical database can be established using open source freeware. The project opens perspectives for a further integration of Wireless Application Protocol phone functions in clinical information processing: Global System for Mobile communication telephony for bilateral communication, asynchronous unilateral communication via e-mail and Short Message Service, built-in calculator, calendar, personal organizer, phone number catalogue and Dictaphone function via answering machine technology. An independent Wireless Application Protocol gateway may be placed within hospital firewalls, which may be an advantage with respect to security. However, if Wireless Application Protocol phones are to become effective tools for physicians, special attention must be paid to the limitations of the devices. Input tools of Wireless Application Protocol phones should be improved, for instance by increased use of speech control.

Clinical Pharmacy Information Systems↗

PubMedDate not supplied

Effects of inhibition of the vacuolar-type proton pump on nephron ultrastructure and acidification in the isolated perfused rat kidney.

The effects of bafilomycin, an inhibitor of the vacuolar-type (V-type) proton pump, on nephron ultrastructure and acidification were analyzed in isolated perfused kidneys from rats with acute metabolic acidosis. Acidic intracellular compartments were labelled with the weak base DAMP, that was subsequently visualized immunocytochemically. The distribution of the proton pump was studied by immunocytochemistry. Bafilomycin inhibited urinary acidification and caused pronounced ultrastructural changes in proximal tubule cells and B-type intercalated cells (B-IC cells). Immunoreactivity for DAMP showed that bafilomycin also inhibits intracellular acidification. The distribution of the proton pump was essentially unchanged by bafilomycin in A-IC cells. In B-IC cells, immunoreactivity accumulated over studded membrane material in the apical cytoplasm. The results indicate that the V-type proton pump is important both for intracellular and for urinary acidification.

Acids↗

PubMedDate not supplied

Effect of spironolactone treatment on the ultrastructure of cortical intercalated cells in the rat kidney.

The ultrastructure of intercalated cells in the rat renal cortex was investigated after 7 days of treatment with the mineralocorticoid inhibitor spironolactone. In untreated and treated animals, two subgroups of IC cells (A-IC and B-IC) could be recognized by electron microscopy, but a substantial fraction of IC cells that corresponded to neither A nor B forms, so-called NonA-NonB, was also found. After spironolactone treatment, qualitative and morphometric analyses showed a decrease in volume density of mitochondria, in cell cross-sectional area, and in boundary length of basolateral membranes in A-IC cells. Among the NonA-NonB-IC cells, some revealed especially abundant mitochondria. Although the frequency of NonA-NonB-IC cells did not change significantly, these mitochondria-rich cells appeared with increased frequency after spironolactone treatment. The ultrastructural changes in A-IC cells might reflect a direct effect of spironolactone on the A-IC cells. However, it is also conceivable that the changes are secondary to functional alterations induced in neighboring segment-specific cells by the experimental conditions.

Animals↗

PubMedDate not supplied

Three-dimensional organization and segmental ultrastructure of rat proximal tubules.

AIMS: To provide a 3-D description and basic morphometric data along the course of subcapsular proximal tubules. METHODS: Proximal convoluted (PCT) and straight (PST) tubules were analyzed in series of up to one thousand 4-micron sections of perfusion-fixed rat renal cortex. Nine proximal tubules were traced through the sections by computer-assisted 3-D reconstruction. Selected sections were reembedded and resectioned for ultrastructural morphometry. RESULTS: Subcapsular PCTs (n = 3) had a total length of 12.0 +/- 0.2 mm (SEM), formed tight clusters and contacted the renal surface from 5 to 10 times. In contrast, mid-cortical tubules (total PT length 11.6 +/- 0.1 mm) and in particular deep cortical tubules (total PT length 12.1 +/- 0.9 mm) extended laterally and intermingled considerably with neighboring tubules. Epithelial height gradually decreased from around 11 microns in the PCT to 7.5 microns in the end of the PST. Brush-border height was around 4 microns in the first PT segment (S1), 2.3 microns in the second segment (S2) and 4.5 microns in the end of the proximal tubule. Tubular wall volume, excluding microvilli, decreased from around 1,450 micron3/microns tubule length in early PCT to 825 micron3/microns in terminal PST. CONCLUSIONS: The results provide, at precisely defined nephron levels, quantitative ultrastructural data relevant to transport physiology.

Animals↗