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B Schönfeld

Publications and source records attributed to B Schönfeld.

13 recordsLinked to original sources
PubMed2002

The asymptotic leading term of anisotropic small-angle scattering intensities. II. Non-convex particles.

For anisotropic particulate samples with scattering contrast (delta n)(2), the leading asymptotic term of the scattering intensity, along a direction q (q/q) of reciprocal space, is [4 pi(2)(delta n)(2)/q(4)]sigmaj [1/kappaG.j(+/-q)]. Here, kappaG.j(+/-q)denotes the Gaussian curvature value at the points (labelled by j) of the interphase surface where the normal is either parallel or antiparallel to q. If the Gaussian curvature vanishes at, say, the jth of these points, the corresponding contribution takes the form Cj/qalpha with 2< or = alphaj<4, Cj and alphaj being determined by the local behaviour of the surface. However, the intensity detected by a counter pixel, with opening solid angle deltaomega(q0) along (mean) direction q0, asymptotically still behaves as 4pi(2) (delta n)(2)(deltaomega(q0))/q(4), where S(deltaomega(q0)) is the area of that part of the interface that has its normals inside deltaomega(q0).

Journal Article↗
PubMed1998

[Umbilical cord blood transplantation: acceptance of umbilical cord blood donation by pregnant patients].

BACKGROUND/OBJECTIVE: Umbilical cord blood is an alternative source for allogeneic transplantation of hematopoietic stem cells from related and unrelated donors. It can easily be collected, cryopreserved and stored in cord blood banks for later use. In Switzerland, cord blood banks for related and unrelated stem cell transplantation are being established. The aim of the study was to evaluate previous knowledge of the possible medical use of cord blood and acceptance of cord blood banking in pregnant women. METHODS: We performed a prospective open study using a structured, anonymous questionnaire at the University of Basel Women's Hospital pregnancy outpatient clinic. After concise information on the use of cord blood for transplantation, questions were asked concerning previous knowledge of the use of placenta and cord blood in general, concerning the attitude to donation of cord blood for transplantation, and the respondent's willingness to donate cord blood of her own child. Women of different ethnic background were compared. RESULTS: From 300 questionnaires handed out to pregnant women of different ethnic background attending our outpatient clinic, 250 (83%) were returned, and 245 could be evaluated for final analysis. Only 40% indicated that they did know what usually happens to the placenta after birth. In contrast, the vast majority (95%) supported the idea of umbilical cord blood for banking and later use for stem cell transplantation. Similarly, 93% stated that they would agree to donate the cord blood from their own child for this purpose, while no statistically significant differences could be identified either between women with or without previous knowledge or of different ethnic background. CONCLUSIONS: This study shows the high acceptance of umbilical cord blood donation for banking and stem cell transplantation purposes in pregnant women, irrespective of previous knowledge. As there are no major differences between women of different ethnic background, a high degree of diversity of HLA-types of donated cord blood samples can be expected and may offset the underrepresentation of ethnic minorities in bone marrow donor registries.

Blood Banks↗
PubMed1994

Dithio-bis-mercaptoethanesulphonate (DIMESNA) does not prevent cellular damage by metabolites of ifosfamide and cyclophosphamide in LLC-PK1 cells.

Ifosfamide (IF) is an alkylating cytostatic with urotoxic (haemorrhagic cystitis) and nephrotoxic (Fanconi syndrome) side effects. Cyclophosphamide (CP), a structural isomer of IF, shows urotoxic but no nephrotoxic side effects. The development of haemorrhagic cystitis during therapy with IF or CP can be prevented by the uroprotective drug sodium-2-mercaptoethanesulphonate (MESNA). However, even in the presence of MESNA, Fanconi syndrome may still develop after therapy with IF. Using the renal tubular cell line LLC-PK1, we investigated whether there is a protective effect of either MESNA or of its major metabolite DIMESNA, in combination with metabolites of IF or CP, on thymidine incorporation, uridine incorporation or total protein. DIMESNA, the dimer of MESNA, is the dominant form of the molecule in the circulation; the proximal tubular cell must convert this back to MESNA at the expense of glutathione, before it can exert its uroprotective action. We did not find a protective effect of DIMESNA under any of the experimental conditions tested. LLC-PK1 cells exposed to 3 mmol/l DIMESNA did not convert DIMESNA to MESNA. The toxic effect of the CP metabolite 4-OOH-CP was more pronounced in the presence of DIMESNA than in its absence. MESNA completely prevented the toxic effects of acrolein and of 4-OOH-CP. The toxic effects of 4-OOH-IF and of chloracetaldehyde, two major metabolites of IF, were significantly reduced in the presence of MESNA. However, even at 30-fold molar excess of MESNA over a 4-OOH_IF, thymidine incorporation remained reduced by 40% compared with controls, indicating incomplete protection of tubular cells against metabolites of IF. Similarly, the effect of chloracetaldehyde was not completely reversed by MESNA.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Toxicity of ifosfamide, cyclophosphamide and their metabolites in renal tubular cells in culture.

Ifosfamide (IF) and cyclophosphamide (CP) are highly effective alkylating cytostatic drugs. IF and CP have to be activated through a metabolic step in vivo; numerous metabolites are known. While both IF and its structural isomer CP have severe urotoxic side effects, only IF is also a nephrotoxic drug, causing tubular damage resulting in Fanconi syndrome in some cases. Little information is available regarding the pathogenic mechanism of tubular damage by IF. We used the renal epithelial cell line LLC-PK1, which has many properties of the proximal tubule, in order to investigate the toxicity of IF and CP and of their reactive metabolites 4-hydroxy-IF (4-OH-IF), 4-hydroxy-CP (4-OH-CP), acrolein and chloroacetaldehyde (CAA). Protein content of monolayers, DNA and RNA synthesis were determined by standard techniques (thymidine and uridine incorporation). IF and CP had the lowest toxicities of all compounds tested. Both drugs inhibited thymidine incorporation by about 30% at a concentration of 300 mumol/l after 1 h incubation. 4-OH-IF and 4-OH-CP were significantly more toxic than the parent drugs. Thymidine incorporation, the most sensitive parameter, was reduced by about 70% by 300 mumol/l of either compound. In addition, 4-OH-CP reduced the total protein content of monolayers. 4-OH-IF did not effect protein content and RNA synthesis. Acrolein, the most toxic metabolite tested, reduced all three parameters significantly at concentrations of 50-75 mumol/l after 1 h.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetaldehyde↗
PubMed1994

[Functional and esthetic results after reconstruction of orbital walls].

From 1985 to 1992 40 patients with large defects of the orbital wall were operated by reconstructive surgery. Defects were caused by trauma (35), facial cleft (3), tumor (1) and osteoradionecrosis (1). Small defects were covered with lyophilised dura mater or thin PDS-film, larger defects with autogenous or xenogenous cartilage, PDS-plates, ceramic plates or titanium micro mesh. After tumor surgery and osteoradionecrosis the orbital wall was reconstructed with free resp. microvascularised bone. In all cases a clear improvement of the initial position was possible. Dislocation of the zygomatic bone should be corrected by osteotomy in order to reconstruct as much as possible of the orbital wall with local bone.

Esthetics↗
PubMed1992

DNA cytophotometric analysis of breast cancer. Follow-up for 10 years.

Forty-four cases of newly diagnosed invasive ductal breast cancer were studied by static cytometry at the time of diagnosis and were followed for 10 years to determine if the survival rate correlated with the nuclear DNA measurements. In 22 cases the stem line was in the 2c range, in 15 cases in the 3c range and in 7 cases in the 4c range. Thirty-four percent (n = 15) of the patients died of metastases during the first five years, 11% (n = 5) died of metastases between 5 and 10 years, and 55% (n = 24) survived for > 10 years without metastases. No correlation between increased tumor cell proliferation and recurrence of tumors could be found. In this study all patients with diploid tumors, tumor size T1 and negative lymph node status survived for > 10 years. In the presence of node metastasis (T1N1M0) all patients (n = 4) having tumors with the stem line in the 2c range survived for 5 years but only 2/4 for > 10 years. The percentage of patients surviving for 10 years showed no significant differences between the groups: in the 2c range, 59% (13/22); in the 3c range, 53% (8/15); and in the 4c range, 43% (3/7). The small number of cases does not allow definitive statistical conclusions, although the logistic regression analyses showed that stem line, pT and pN were the important prognostic factors for five-year survival. However, only pT and especially pN were of prognostic value for 10-year survival.

Breast Neoplasms↗
PubMedDate not supplied

Inhibition of sodium-dependent transport systems in LLC-PK1 cells by metabolites of ifosfamide.

Ifosfamide (IF) is an alkylating cytostatic derived from nitrogen mustard. In addition to its well-known urotoxic effects (hemorrhagic cystitis), several cases of Fanconi syndrome following IF therapy have been reported. No information is available concerning the pathomechanisms of this tubulotoxicity. We used the permanent renal epithelial cell line LLC-PK1 in order to investigate whether major metabolites of IF (i.e. 4-OH-IF, acrolein and chloracetyldehyde) induced the transport defects most frequently detected after IF therapy in vivo. LLC-PK1 cells of passages 162-177, grown in plastic culture dishes, were used in a confluent state. Sodium-dependent and independent fluxes of l-[3H]alanine and of D-[3H]glucose were determined by standard techniques. Activities of marker enzymes of apical and basolateral membranes, of mitochondria and of endoplasmic reticulum were determined in cell homogenates. IF itself has no detectable effect on fluxes of l-alanine and D-glucose in LLC-PK1 cells. The IF metabolite 4-OOH-IF induces a clear inhibition of sodium-dependent fluxes of both substrates after a 24-hour exposure of cells to 100 mumol/l of 4-OOH-IF. Chloracetaldehyde induces a biphasic response of sodium-dependent fluxes of l-alanine with increased uptake rates at low concentrations (< 200 mumol/l) and with a short incubation time, while higher concentrations and long exposure of the cells leads to a reduction in sodium coupled transport. Glucose transport is affected in a comparable way, however, in contrast to alanine transport, chloracetaldehyde also stimulates sodium-independent fluxes of glucose. Acrolein is the most toxic substance tested. It severely damages cell monolayers at concentrations beyond 75 mumol/l. Sodium-coupled glucose and alanine transport is inhibited by acrolein at concentrations higher than 50 mumol/l. Sodium-coupled glucose transport is more sensitive to all metabolites tested than alanine transport. While acrolein strongly affects both transport systems, marker enzymes of the apical plasma membrane, i.e. alkaline phosphatase and leucine amino-peptidase, are not significantly inhibited, suggesting a specificity of the toxic effect for the transport proteins. We conclude that LLC-PK1 cells represent a good model for further investigation of the pathogenesis of Fanconi syndrome after IF therapy. Sodium-dependent transport systems are more sensitive to acrolein than other cell surface proteins.

Acetaldehyde↗
PubMedDate not supplied

Effect of ifosfamide metabolites on sodium-dependent phosphate transport in a model of proximal tubular cells (LLC-PK1) in culture.

Ifosfamide (IF) is an alkylating cytostatic drug with urotoxic (hemorrhagic cystitis) and nephrotoxic side effects. Several cases of Fanconi syndrome in children following therapy with IF were reported. Little information is available concerning the pathomechanisms of transport inhibition by IF. We used a permanent renal epithelial cell line with proximal tubular characteristics (LLC-PK1) in order to investigate the effects of IF and some of its major metabolites (4-OH-IF, chloracetaldehyde, and acrolein). LLC-PK1 cells were used in a confluent state. Sodium-dependent and sodium-independent fluxes of 32PO4 were determined by standard techniques. Activities of marker enzymes of apical and basolateral membranes, of mitochondria, and of endoplasmic reticulum were determined in cell homogenates. IF induces a moderate stimulation of PO4 transport. 4-OH-IF also has a stimulatory effect on transport at low concentrations (up to 200 mumol/l) and with short incubation (2h), while a 24-hour exposure of cells to 100 mumol/l of 4-OH-IF has an inhibitory effect of PO4 transport. Concentrations of 4-OH-IF which inhibit transport also reduce the activity of Na(+)-K(+)-ATPase. Chloracetaldehyde, like 4-OH-IF, induces a biphasic response of PO4 transport with stimulation in the low concentration range (up to 75 mumol/l) and inhibition at higher concentrations. Chloracetaldehyde reduces the activity of succinate-cytochrome c oxidoreductase, suggesting that a defect in ATP generation might play a role in the pathogenesis of Fanconi syndrome induced by IF. Acrolein strongly damages monolayers and reduces sodium-dependent transport of PO4 to very low levels at 150 mumol/l. It reduces the activities of both Na(+)-K+ ATPase and succinate-cytochrome c oxidoreductase. Acrolein also is the only metabolite with a moderate effect on alkaline phosphatase. We conclude that sodium-dependent transport of PO4 is highly sensitive to IF metabolites. In addition to direct toxic effects of IF metabolites on transport proteins within the apical plasma membrane, damage to mitochondrial enzymes and to Na(+)-K+ ATPase which generates the electrochemical gradients for secondary active PO4 transport may play an important role in the pathogenesis of Fanconi syndrome induced by IF.

Acetaldehyde↗