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Biomedical subjects

W Pfaller

Publications and source records attributed to W Pfaller.

At least 19 recordsLinked to original sources
PubMed1992

In vitro and in vivo effect of antibiotics on catheters colonized by staphylococci.

An in vitro model was used to study whether and how catheter infections can be cured. Silastic catheters were "infected" with Staphylococcus aureus ATCC 25923 and Staphylococcus epidermidis KH11 and V2; these "infections" were then treated with 24, 48 and 96 h continuous infusions of various antimicrobial agents administered both as monotherapy and in combination. The Staphylococcus aureus strain was considerably more difficult to eliminate from catheters than were the Staphylococcus epidermidis strains. This experience gained in the laboratory was then applied in vivo to 16 episodes of catheter sepsis in seven children. Treatment for at least six days with imipenem/cilastatin combined with fosfomycin or an aminoglycoside successfully eliminated the pathogens isolated from 11 of the 16 episodes of infection. The broad-spectrum combination was chosen because it could not be assumed that individual pathogens would be sensitive to a single substance. Nine of the infected catheters could be retained in the patients. This experience suggests that it may be possible to successfully eliminate the colonization of central venous catheters by coagulase-negative staphylococci using the antimicrobial agents employed here.

Anti-Bacterial Agents↗
PubMed1992

Tissue distribution of neutrophils in postischemic acute renal failure.

Polymorphonuclear neutrophil granulocytes (PMNs) seem to participate in the pathogenesis of renal ischemic reperfusion injury. The kidneys from male Sprague Dawley rats were immersion-fixed after 45 min of renal artery clamping followed by reperfusion for 0, 5, 20, and 120 min, respectively. The tissue distribution of PMNs in the kidneys was studied histochemically using naphthol AS-D chloroacetate esterase as a specific marker for these cells. Neutrophil counts per unit sectional area were obtained for renal cortex, outer and inner medulla. In the cortex separate intraglomerular and peritubular counts, and in the outer medulla separate outer and inner stripe counts were made. After 120 min of reperfusion the total renal PMN counts were 488 +/- 62 (n = 4) compared with 54 +/- 4 (n = 4) per cm2 in nonischemic controls. Within 120 min of reperfusion PMN counts increased by a factor of 8 in the cortex, of 12 in the outer medulla and of 14 in the inner medulla, compared with controls. The ratio of intraglomerular against peritubular PMN counts was approximately 2 in controls, but 0.5 after a 120-min reperfusion interval. The outer stripe of the outer medulla contained only a small number of PMNs whereas PMN counts of 923 +/- 197 (n = 4) per cm2 were found in the inner stripe after 120 min reperfusion. Interestingly, there was a marked increase in PMNs in the inner stripe during the first 5 min of reperfusion but no extravasation of PMNs was observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Kidney Injury↗
PubMed1992

Ammoniagenesis in LLC-PK1 cultures: role of transamination.

The LLC-PK1 renal epithelial cell line has been used as a model system to study renal ammoniagenesis and its regulation by metabolic acidosis in vitro. Experiments were performed on confluent LLC-PK1 epithelia grown for 10-14 days in conventional monolayer technique. After the medium pH was changed from 7.6 to 7.0 for 24-72 h by lowering the bicarbonate concentration in culture medium, LLC-PK1 cells responded with an adaptive increase in glutamine consumption and ammonia production. The rates of glutamine uptake and ammonia generation displayed a ratio of 1:1, i.e., 1 mol ammonia was produced per mole of glutamine consumed. Glutamine consumption and ammonia formation were paralleled by an equimolar production of L-alanine, indicating that transamination appears to be the main ammoniagenic pathway in LLC-PK1 cells. Analysis of the key enzymes of renal ammoniagenesis, phosphate-dependent glutaminase (PDG) and glutamate dehydrogenase (GDH), revealed no changes in enzyme activities up to 72 h of adaptation. Alanine aminotransferase (ALT) activity in LLC-PK1 cells also remained unchanged during the adaptation period. Because transamination seems to play a crucial role in channeling the metabolic flux in LLC-PK1 ammoniagenesis, experiments were performed in which transamination was inhibited by (aminooxy)acetate (AOA). After incubation of control and pH 7.0-adapted LLC-PK1 cultures for 24-72 h in 0.2 mM AOA, no alanine production was found, but 2 mol of ammonia were formed per mole of glutamine consumed, again, without adaptive changes in PDG and GDH activities.(ABSTRACT TRUNCATED AT 250 WORDS)

Acidosis↗
PubMed1990

Morphology of the differentiation and maturation of LLC-PK1 epithelia.

In the present study, a stereologic approach was utilized to quantitatively assess morphological changes during the differentiation of LLC-PK1 cells into an epithelial membrane. This renal epithelial cell line has been described to undergo morphological changes during differentiation and maturation from subconfluent culture to a confluent epithelial layer. An increase in the number of apical microvilli, interpreted as an areal increase in this membrane domain was reported. This morphological differentiation was found to be accompanied by an increase in the expression of apical Na(+)-dependent hexose transport and the activities of certain brush border enzymes. Since no data are available that quantify the morphologic changes during LLC-PK1 differentiation, a quantitative morphologic-stereologic-investigation was performed for an early (6 days) and a late (12 days) state of confluence of LLC-PK1 monolayer cultures. The following morphological parameters were determined by light and electron microscopic morphometry: volume fractions (Vv) of nuclei, mitochondria, and lysosomes, and surface densities (Sv) of the apical and basolateral cell membrane domains. For the apical membrane surface, the microvillous fraction has been measured separately. Since the stereologic approach used in the present study allows the determination of absolute cell volumes, the absolute measures of organelle volumes (V) and membrane surfaces (S) per average cell can be calculated from volume and surface densities. Although no changes in cell density were found for 6 and 12 day old LLC-PK1 monolayers, indicating ceased cell proliferation due to contact inhibition, remarkable changes were found concerning the absolute cell volume and apical membrane surface. The observed increase in the apical cell surface was exclusively due to the enlarged microvillous surface fraction. This finding is in good agreement with the increased number of Na(+)-dependent hexose transporters as well as with the increased expression of apical membrane marker enzymes observed during the differentiation of LLC-PK1 monolayers.

Animals↗
PubMed1990

Madin-Darby canine kidney cells. III. Aldosterone stimulates an apical H+/K+ pump.

Functionally and morphologically, Madin-Darby canine kidney (MDCK) cells resemble intercalated cells of urinary epithelia. Experiments were performed on domes of confluent MDCK monolayers to test for apical H+ secretion. Apical application of 10(-3) mol/l amiloride or of Na(+)-free solution significantly reduced the limiting pH gradient across the dome epithelium (delta pHd) consistent with inhibition of apical Na+/H+ exchange. Short-circuit current (SCC) measurements disclosed an acetazolamide-sensitive, (basolateral to apical) positive transepithelial current stimulated by 10(-7) mol/l aldosterone and inhibited by acidification of apical medium to pH = 4.5. Histochemical evaluation of carbonic anhydrase (CA) activity revealed cytoplasmic and apical-membrane-bound CA particularly in dome-forming cells. Apical substitution of Na+ by K+ increased delta pHd, whereas a reduction of K+ concentration to 0.5 mmol/l or addition of barium or omeprazole (10(-5) mol/l) to the apical superfusate reduced delta pHd by at least 75%. Aldosterone-stimulated SCC was completely abolished by the apical application of barium. We conclude that besides Na+/H+ exchange MDCK cells can express an apically located H(+)-K+ pump stimulated by aldosterone and inhibited directly by the anti-ulcer agent omeprazole or indirectly, either by blocking apical K+ recycling or by interfering with the CA-dependent intracellular formation of H+ ions.

Aldosterone↗
PubMed1990

Morphology of renal tubular damage from nephrotoxins.

The proximal renal tubular cells' vulnerability to the direct toxic action of chemicals is largely due to the role played by this nephron portion in absorption and secretion. This is an energy-demanding function so that these cells must have a high rate of oxidative metabolism and thus contain many mitochondria supplying the Na+/K+ pumps at the basolateral plasma membrane domain, thereby driving the carrier systems for entry of water and solutes across the luminal membrane. Thus toxic mechanisms leading directly or indirectly to disturbances of the renal cells' energy metabolism will result in cell injury and acute renal insufficiency. Quantitative morphological-stereological-analysis of at least two, the mercuric chloride- and the maleate-induced experimental models of toxic acute renal failure, show a very early substantial loss of ATP-generating mitochondrial inner membrane surface as well as substantial decrease in those functions protecting cells against oxidative or auto-oxidative processes, i.e. glutathione content, activities of the free-radical-scavenging systems superoxide dismutase, glutathione peroxidase and glutathione reductase and catalase. The cellular dysfunction following these early events may be considered as causative of the subsequent development of most of the morphological alterations described, which are fairly similar in appearance regardless of the toxic principle acting upon the kidney.

Acute Kidney Injury↗
PubMed1990

Xanthine oxidase: evidence against a causative role in renal reperfusion injury.

The conversion rates of xanthine dehydrogenase (XDH) to xanthine oxidase (XO) were compared with the time course of in vivo lipid peroxidation (LPO) in an ischemia-reperfusion model of acute renal failure in the rat. LPO, measured as the renal release of malondialdehyde (MDA), was found to be markedly elevated only during the first 5 min of blood reflow following a 45-min interval of ischemia (arteriovenous MDA difference -277.3 +/- 53.5 vs. 3.7 +/- 5.7 nmol/l in controls, n = 14). After 30 min of reperfusion, arteriovenous MDA differences nearly reached control values (9.7 +/- 31.8 nmol/l, n = 7). In contrast to enhanced LPO, no significant conversion of XDH to XO was found (XO activity in controls: 23 +/- 1% of XO plus XDH activity vs. 26 +/- 3% after 45 min of ischemia, n = 7). Therefore XO-derived superoxide anion radicals cannot be considered causative for LPO in the reperfusion interval of experimental ischemic acute renal failure.

Animals↗
PubMed1989

Fusion of cultured dog kidney (MDCK) cells: I. Technique, fate of plasma membranes and of cell nuclei.

The evaluation of the intracellular signal train and its regulatory function in controlling transepithelial transport with electrophysiological methods often requires intracellular measurements with microelectrodes. However, multiple impalements in epithelial cells are hampered by the small size of the cells. In an attempt to avoid these problems we fused cells of an established cell line. Madin Darby canine kidney cells, originally derived from dog kidney, to "giant" cells by applying a modified polyethylene glycol method. During trypsin-induced detachment from the ground of the petri dish, individual cells grown in a monolayer incorporate volume and mainly lose basolateral plasma membrane by extrusion. By isovolumetric cell-to-cell fusion, spherical "giant" cells are formed within 2 hr. During this process a major part of the individual cell plasma membranes is internalized. Over three weeks following cell plasma membrane fusion degradation of single cell nuclei and cell nuclear fusion occurs. We conclude that this experimental approach opens the possibility to investigate ion transport of epithelia in culture by somatic cell genetic techniques.

Animals↗
PubMed1988

Noninvasive diagnosis of renal allograft rejections--application of an information-theoretical model.

This paper describes an information-theoretical model developed for detection of renal allograft rejection on the basis of various laboratory data. In this report the mathematical background of the model is described in detail and the rationale of its use is discussed. An example is given for the practical application of the model in kidney grafted patients. In the 30 patients of the test collective, seven rejection episodes were diagnosed by the clinicians and verified histologically. All seven rejection episodes were detected by the model, in the mean 2.4 days (median; 3 days) before the clinical diagnosis.

Biopsy, Needle↗
PubMed1988

Toxic properties of the mushroom Cortinarius orellanus. I. Chemical characterization of the main toxin of Cortinarius orellanus (Fries) and Cortinarius speciosissimus (Kühn & Romagn) and acute toxicity in mice.

The toxins of the mushrooms Cortinarius orellanus (Fries) and Cortinarius speciosissimus (Kühn & Romagn) were isolated by extraction procedures and Sephadex chromatography. All intermediate and end products of the purification process were tested in mice for acute toxicity after oral and i.p. administration. In both species a fluorescent main toxin and a nonfluorescent compound of minor toxicity were found. The main toxin of both species was identified by mass spectrometric and nuclear magnetic resonance analyses as the 2,2'-bipyridine-3,3',4,4'-tetrol-1,1'-dioxide, which is identical to orellanine. The purified compound was toxic when administered either orally or i.p. When given orally the LD50 was 33 mg/kg body weight in mice. The oral LD50 of Cortinarius orellanus (2.20 g dried mushroom/kg) and of Cortinarius speciosissimus (3.12 g/kg) depended on the orellanine content (14 mg/g in Cortinarius orellanus and 9 mg/g in Cortinarius speciosissimus). The second toxic component was ineffective in mice when given orally. It caused acute toxicity when administered i.p., but toxicity was low when compared to the main toxin. Thus it appears to be of minor importance. Intraperitoneal testing of both isolated toxins and of the extract containing the whole toxic potential of the mushrooms revealed that toxicity, time dependency and expression of toxicosis is accounted for by the sum of these two toxins. No peptidic main toxin as described by other mycologists could be detected.

2,2'-Dipyridyl↗
PubMed1988

Toxic properties of the mushroom Cortinarius orellanus (Fries). II. Impairment of renal function in rats.

Oral administration of the toxic mushroom Cortinarius orellanus (Fr.) to male Sprague Dawley rats caused serious impairment of renal function. The signs observed were similar to those produced in humans who ingest this fungus. Administration of 2.0 g dried Cortinarius orellanus per kg body weight led to acute renal dysfunction within 48 h. The pattern of impairment included reduced glomerular filtration rate, decreased renal absorption of water, sodium and potassium, and proteinuria and glucosuria. The nephrotoxic effect was further characterized by decreased activities of the brush border enzymes alkaline phosphatase and gamma-glutamyltranspeptidase in urine, despite a remarkable increase in protein excretion of predominantly tubular origin. These findings were substantiated by morphologic changes, which could be detected as early as 12 h after dosing. Morphologically discernible signs of renal tubular damage start with deformation of the proximal tubular brush border region. Within 48 h after toxin ingestion, prenecrotic and necrotic cells could be found in all nephron segments contained in the renal cortex. The most prominent changes were a vesiculation of the apical cell pole and a swelling of the smooth surfaced endoplasmic reticulum and of mitochondria. The latter was accompanied by a loss in matrix material and a massive fragmentation of mitochondrial cristae membranes. Detectable quantities of the toxic principle of the mushroom, orellanine, were excreted only within the first 24 h after dosing. No impairment of liver function was detected.

Agaricales↗
PubMed1988

Comparison of serum neopterin levels and urinary neopterin excretion in renal allograft recipients.

Determination of serum and urinary neopterin levels was performed daily in 30 patients undergoing kidney transplantation for treatment of end-stage renal failure. Neopterin serum levels were determined by RIA and urinary excretion by HPLC. In parallel, the same samples were tested for creatinine content. Results indicated a strong correlation between the clearance of neopterin and creatinine. This correlation was independent of the extent of functional impairment as well as of the different causes of renal insufficiency. As a consequence, a strong relationship between serum and urinary neopterin levels was only obtained when values were corrected for different renal function by dividing them by the creatinine levels. It thus appears that major attention has to be paid to the functional state of the kidney when studying neopterin serum and/or urine values. It also appears that under these prerequisites both methods of detection as well as both sample sources yield comparable results.

Adult↗
PubMed1987

Local injection of cysteamine into the rat striatum decreases number and intensity of staining of neurons by indirect NADPH diaphorase reaction.

Cysteamine (100 micrograms) markedly reduces the number (by about 60%) and intensity of staining of NADPH diaphorase-reactive neurons 6 h after local injection into the striatum. This effect was reversible (after 24 h) and was only observed when the indirect staining procedure was applied in which NADPH formed by endogenous malate dehydrogenase is used. However, no direct effect of cysteamine on the malate dehydrogenase reaction was found. The decrease in NADPH diaphorase activity parallels the previously reported cysteamine induced decrease in somatostatin contained in the same neurons and may point to a biochemical interrelation of somatostatin and NADPH diaphorase in these neurons.

Animals↗
PubMed1986

Urinary enzyme analysis in renal allograft transplantation.

The urinary excretion of four enzymes (fructose-1,6-bisphosphatase, glutathione S-transferase, N-acetyl-beta-D-glucosaminidase and pyruvate kinase) was assayed daily in 59 patients following renal cadaveric allografting. 51 patients were given cyclosporin A (CyA group) as an immunosuppressive, 8 patients were treated conventionally with azathioprine and prednisolone (CON-group). Urinary enzyme output was evaluated by two different mathematical models. Model A follows single enzyme excretion, whereas model B also analyzes enzyme patterns. The best results were obtained by a combined analysis of all four enzymes with model B. In the CON-group the sensitivity was 1.00, the specificity 0.85, the predictive values of positive test 0.45 and all 12 graft rejections were diagnosed correctly. In the CyA group the sensitivity was 0.40, the specificity 0.99, the predictive value of positive test 0.33, and 6 out of 9 rejections were recognized. The evaluation of the single enzymes did not produce similarly good results with either model.

Acetylglucosaminidase↗
PubMed1986

Macrophage infiltration in non-Hodgkin's lymphomas: a quantitative in situ study.

The frequency and distribution pattern of macrophages within 93 non-Hodgkin's lymphomas (NHL) were evaluated in situ by immunomorphometry using stereological methods. For the identification of macrophages (M phi), several antibodies (Mono 1, Mono 2, OKM 1) reactive with surface antigens on cells of the monocyte-macrophage series and cytochemical staining for acid phosphatase were applied. The average number of macrophages within lymph node tissue of NHL was 6,299 +/- 760 cells/microliter (similar to reactive lymphatic tissue: 6,559 +/- 1,027). The highest number of infiltrating macrophages was detected in immunoblastic NHL (17,306 +/- 2,773), differing significantly from other histological subtypes and reactive lymphatic tissue (p less than 0.005). The possible impact of tumor-infiltrating macrophages on lymphoma cell proliferation and differentiation is discussed.

Antibodies, Monoclonal↗
PubMed1986

Morphological and biochemical observations in rat nephron epithelia following cyclosporine A (CsA) treatment.

Morphology, urinary enzyme excretion and mitochondrial function was studied in rats fed over a period of 30 days with 20 and 40 mg CsA/kg body weight. Already on day 8 vacuolisation and augmentation of autophagic vacuoles, lipid droplets and a loss in microvilli can be observed in the S-3 segment of the proximal nephron using the lower CsA dose. These effects are enhanced during the treatment period. The overall effect, however, is a subtle one. The dose of 40 mg/kg produces more pronounced cellular alterations, a more severe vacuolisation, but also focal prenecrotic damage of proximal tubular S-2 and S-3 cells. The cells altered in that manner amount to roughly 5% of the total proximal tubular epithelium. Enhanced urinary excretion of the proximal cytosolic enzymes, fructose-1,6-bisphosphatase, glutathione S-transferase, pyruvate kinase and the lysosomal N-acetyl-beta-D-glucosaminidase appear to parallel the morphologic changes, whereby only the excretion of pyruvate kinase is significantly elevated on day 30 using 40 mg/kg. Decrease in oxidative phosphorilation capacity (ADP:O ratio) was found with both CsA doses, however, this result seems to be dissociated from changes in morphology and enzyme excretion. Studies on isolated tubular fragments in vitro, exposed to CsA exhibited an inhibition of the cytosolic malate dehydrogenase isoenzyme, which could be interpreted as a possible source of the CsA induced tubular alteration.

Acetylglucosaminidase↗
PubMed1985

[Infiltration pattern of immunocompetent lymphocytes in the tissue of malignant non-Hodgkin's lymphoma: relationship to histological and clinical parameters].

The number and distribution of reactive cells in more than 100 non-Hodgkin lymphomas (NHL) were evaluated in situ in cryostat sections. The results were compared with histological and clinical findings. 40% of the T cell content of normal lymphatic tissues was found in tissues of B-cell NHL. This corresponds to a mean of 2 X 10(4) reactive T-cells/microliter tumour tissue. The numerical density of natural killer (NK) cells within tumours was similar to that of normal lymphatic tissues (0.5 X 10(4) cells/microliter). The distribution of the reactive cells within the tumours was diffuse except in the case of centroblastic/centrocytic lymphomas. On evaluation of the different histological entities a significant correlation was obtained between number of helper/inducer (TH) cells, TH:T-suppressor (Ts) ratio and prognostically favourable histological subgroups. Furthermore, independent of histological criteria, a close correlation was found between a high number of TH-cells, a high TH:Ts ratio and a favourable clinical course (p less than 0.04). NK-cell infiltration was present to a markedly higher extent in tissues of patients with generalized disease as compared with localized disease (p less than 0.03). Low-grade malignant NHL contained significantly more NK cells than high-grade malignant NHL, as was the case also in treated, as opposed to untreated patients. These findings together suggest that reactive cells influence tumour growth via local interactions. However, tissue distribution and infiltration density of T-cell subpopulations and NK cells were clearly different. Thus, in tumour tissues different and independent immunoregulatory mechanisms seem to be associated with these two lymphocyte subsets.

Antibodies, Monoclonal↗