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W Schmidt

Publications and source records attributed to W Schmidt.

At least 55 records · Page 3Linked to original sources
PubMed2002

[Characteristic mechanical properties of balloon-expandable peripheral stent systems].

PURPOSE: To measure in vitro geometric-mechanical characteristics of balloon-expandable peripheral stent systems for determining suitability for specific vascular regions. MATERIALS AND METHODS: Balloon-expandable stents including their delivery systems manufactured by Guidant (OTW Megalink trade mark ), Inflow Dynamics (Antares), Medtronic (AVE Bridge trade mark ), Biotronik (Peiron trade mark ) and Cordis (Corinthian IQ trade mark ) were selected for this study. When expanded, all stents had a nominal diameter of 8 mm. The length was 38 - 40 mm. Stent profile, trackability, length change on expansion, stiffness, elastic recoil, and radio-opacity in the crimped and expanded state of these stent systems were determined with specially developed test methods. RESULTS: The Corinthian IQ trade mark, Megalink trade mark and Peiron trade mark required the smallest force to pass through the vascular model. While the Bridge trade mark system had the largest profile with a diameter of 2.430 mm, all other stent systems had a significantly smaller diameter ranging from 1.970 mm for the Peiron trade mark to 2.078 mm for the Corinthian IQ trade mark. In the distal region of the stent delivery system, the Megalink trade mark was the most flexible and the Bridge trade mark system the stiffest. Elastic recoil for all stents was in the range of 2.5 % to 3.5 %, with the exception of the Bridge trade mark stent, which had an elastic recoil of 4.79 %. The Corinthian IQ trade mark stent had noticeably the highest radial stiffness. In the expanded condition, the Peiron trade mark was the most flexible while the Corinthian IQ trade mark and the Antares trade mark were found to be the stiffest. Length change (shrinkage on expansion) ranged from 0.54 to 6.57%, with the exception of the Corinthian IQ, which shrunk > 7mm (18.5%) on expansion. All stent systems in the crimped and expanded state were readily visible radiographically. CONCLUSION: Specific data of significant parameters are available to aid in the selection of balloon expandable stents systems to be deployed in complex vascular regions. All examined stent systems showed adequate mechanical properties, but clinically relevant differences were found in stent trackability, bending stiffness and shrinkage on expansion.

Angioplasty, Balloon↗
PubMed2002

Omphalocele and gastrochisis.

Between January 1989 and November 1996 we detected a total of 44 cases of anterior abdominal wall defects comprising 29 with an omphalocele and 15 with gastrochisis. The gestational age at antenatal diagnosis of gastrochisis (mean = 17 weeks, 95% CI = 15-19) was significantly lower than for omphalocele (mean = 19.0 weeks, 95% CI = 17-21). Whereas gastrochisis tended to occur in relatively younger mothers (mean age = 23 years), omphalocele was associated with a comparatively advanced maternal age (mean age = 28 years). The sensitivity of ultrasound detection was the same for both malformations (omphalocele = 86.2%; gastrochisis = 86.7%). Additional structural anomalies were found in a higher proportion of those with an omphalocele compared with those with gastrochisis (62% vs. 20%). All the three cases of chromosomal anomalies were detected in omphalocele fetuses with an intracorporeal liver. Perinatal mortality was higher, albeit nonsignificantly, among fetuses with omphalocele.

Adult↗
PubMed2002

Steric and electrostatic effects in dye-cellulose interactions by the MTD and CoMFA approaches.

This paper presents the application of the MTD (minimal steric difference) analysis and CoMFA (comparative molecular field analysis) to series of anthraquinone vat, mono and disazo and disperses dyes with known affinities for cellulose fiber. A comparison of the results demonstrates that these methods usually agree with the prediction of structural features favorable for dyeing. A series of n = 49 anthraquinone vat dyes was studied by MTD with r2 between 0.903 and 0.941 and r2CV values in the range of 0.827-0.878. For CoMFA, r2 = 0.992, r2CV = 0.841 were obtained; the CoMFA field is in rather good agreement with vertex attributions, by MTD for attractive and repulsive vertices. Anionic disazo dyes were studied by the CoMFA method (n = 21, r2 = 0.999, r2CV = 0.703). Monoazo dyes (several series) were studied by CoMFA and MTD. The effect of lipophilicity on dye fiber affinity was, also, studied for these dyes. Disperse dye adsorption was analyzed by MTD and CoMFA (n = 27, r2 = 0.925, r2CV = 0.776). Conclusions refer to the effect of structural features of dye molecules upon adsorption on cellulose fibers.

Adsorption↗
PubMed2002

Trackability, crossability, and pushability of coronary stent systems--an experimental approach.

Trackability, crossability and pushability are essential properties determining the handling characteristics and deliverability of stent systems. We present objective test methods to assess these parameters quantitatively in an in vitro model. The model consisted of a 6F guiding catheter, a guide wire (0.014") and a coronary vessel model (HD-PE tubing, I.D. 2.5 mm), all immersed in 37 degrees C water. Two attached sensors measured the reactive forces occurring at the proximal catheter shaft and the distal catheter and stent segments during model passage. For crossability assessment, the setup was completed by a stenosis model, mimicking two types of eccentric circular stenoses. A comparative study provided distinctive differences in trackability, stenosis crossability, and pushability. Analyzing the proximal and distal force measurements, these differences were quantified and the qualification of a particular stent system to be successfully delivered to a model target stenosis could be rated.

Angioplasty, Balloon, Coronary↗
PubMed2002

[Comparative analysis of in vitro test procedures for evaluating hemocompatibility of cardiovascular stents].

Within the scope of this study existing in vitro techniques for testing the hemocompatibility of coronary stents were analysed and optimised. Static and quasi-stationary systems were compared to a pulsed flow model with respect to platelet activity. The streamlines were visualized by dye injection. Blood flow was measured by ultrasonic Doppler velocity meter and electromagnetic flow meter. Uncoated stainless steel (316 L) stents were tested. Surrogate parameters of the hemocompatibility were the change in surface morphology after blood contact and the rise of biomechanical activation markers as C3a and beta-thromboglobulin. The results were correlated to the stent design and to the flow characteristics of the test systems.

Angioplasty, Balloon, Coronary↗
PubMed2002

Prenatal diagnosis of sacrococcygeal teratoma: a review of cases between 1993 and 2000.

Sacrococcygeal teratoma is the most common fetal neoplasm with a reported incidence of 1 in 30,000 to 40,000 births. Affected fetuses carry a high perinatal mortality and morbidity. The aim of this retrospective study was to assess prenatal sonographic aspects and pathological details of our cases with sacroccocygeal teratoma. Over the last seven years we identified six cases by retrospective chart review in our institution. Four fetuses were electively aborted, in two of these four fetuses the diagnosis was made before the 16th week of gestation. Two caesarean sections were performed at 35 + 5 and 37 + 0 weeks of gestation, respectively. In those two cases the diagnosis was only made in the late second and third trimester. No case of neonatal mortality occurred. In one of the two resected sacroccocygeal teratomas potential malignancy was diagnosed. A multidisciplinary approach seems advisible for optimal perinatal management.

Abortion, Induced↗
PubMed2002

Significance of high and normal neonatal nucleated red blood cell count in small-for-gestational-age newborns.

The objective of this study was to evaluate the obstetrical and neonatal outcome in small-for-gestational age (SGA) and appropriate-for-gestational-age (AGA) fetuses with normal and elevated neonatal nucleated red blood cell counts. Therefore the nucleated red blood cell count was assessed immediately after birth in 906 neonates delivered at our institution and the perinatal and neonatal data were compared. Postnatally, infants were classified as SGA if they had a birth weight for given gestational age below the 10th percentile. Neonates were allocated to four groups according to their nucleated red blood cell count: SGA neonates with normal and high nucleated red blood cell count and appropriate-for-gestational-age newborns (AGA) with normal and high nucleated red blood cell count. Statistical analysis included the Mann-Whitney U-Test, Student's t-test, chi2 analysis of variance and stepwise regression analysis. SGA newborns with high nucleated red blood cell count had a significantly lower birth weight, a lower gestational age at delivery, lower arterial and venous pH values, lower Apgar scores at 1 min, 5 min and 10 min as well as lower base excess values compared to the other groups. They had to be transferred significantly more often and stayed longer in the neonatal intensive care unit. Three cases of intraventricular hemorrhage, four cases of necrotizing enterocolotis and two neonatal deaths occurred all in the SGA group with high neonatal nucleated red blood cell counts. Neonatal outcomes of SGA and AGA newborns with normal nucleated red blood cell counts were comparable. Our data do therefore underline the possible value of neonatal nucleated red blood cell counts to differentiate the healthy small-for-gestational age newborn from the truely growth retarded newborn.

Apgar Score↗
PubMed2002

Unilateral massive ovarian edema (MOE): a case report.

Massive ovarian edema is an unusual cause of ovarian enlargement in young patients. Venous end lymphatic obstruction producing edema is thought to be the reason for enlargement of the ovaries in most cases. We report the case of a 23-year-old woman with unilateral massive ovarian edema, findings on ultrasound imaging, and a review of the literature. The ultrasound findings have been reported as a solid tumour-like mass or as a solid mass containing a cystic component, which is non-specific and can mimic neoplasia. Thus, the definitive diagnosis requires histological examination. Because conservative treatment with preservation of the ovaries is often possible, ovarian edema is an important condition to consider in a young patient with a complex but non-specific ovarian mass and appropriate preoperative clinical treatment should be started.

Adult↗
PubMed2002

Nucleated red blood cell counts in growth-restricted neonates with absent or reversed-end-diastolic umbilical artery velocity.

OBJECTIVE: To determine the effect of increasing circulatory impairment in fetuses on the neonatal nucleated red blood cell count. METHODS: Seventy-seven fetuses with suspected intrauterine growth restriction (abdominal circumference < 5th percentile), subsequent birth weight < 10th percentile for gestational age and abnormal umbilical artery Doppler flow velocity were enrolled in the study. Fetuses were assigned to the following groups on the basis of the last Doppler examination before delivery: group 1, umbilical artery S/D ratio > 2 SD above the gestational age mean, group 2, absent end-diastolic velocity in the umbilical artery, group 3, reversed end-diastolic velocity in the umbilical artery. Neonatal nucleated red blood cells were obtained from the umbilical artery within 1 min after delivery with follow-up examinations until the nucleated red blood cell count was < 5/100 white blood cells. Perinatal and neonatal data were recorded from the charts. RESULTS: Significantly higher nucleated red blood cell counts [median 144, range 9-964] with lowest birth weights [mean 932 g, range 530 g-2060 g] were detected in group 3 and in group 2 [median 65, range 2-720; mean 1049 g, range 630 g-2110 g] compared to group 1 [median 22, range 2-201; mean 1565 g, range 860 g-2780 g, p < 0.001, respectively]. The persistence of nucleated red blood cells in the neonatal circulation was prolonged in group 3 [median 5.2, range 1-13 days] compared to group 2 [median 3.9, range 1-81 and group 1 [median 1, range 0-2]. Neonates in group 3 also had decreased platelet counts, hematocrit and hemoglobin values. Cord blood gases showed a significant decrease of arterial and venous pH values in groups 2 and 3 which was accompagnied by a significant decrease in base excess values. Four neonatal deaths, three of them in the reversed-end-diastolic velocity and one in the absent end-diastolic velocity group, occurred. Stepwise regression demonstrated that absent or reversed end-diastolic flow velocities, birth weight, gestational age and arterial base excess contribute significantly to the elevation of the nucleated red blood cell counts. CONCLUSIONS: Increased nucleated red blood cell counts at birth and their longer persistance in the neonatal circulation are associated with antenatal abnormal umbilical artery Doppler studies in growth restricted fetuses. The nucleated red blood cell count might therefore become an additional valuable tool in the diagnosis of growth restricted fetuses who are metabolically compromised.

Erythrocyte Count↗
PubMed2001

Suprahepatic venacavaplasty (cavaplasty) with retrohepatic cava extension in liver transplantation: experience with first 115 cases.

BACKGROUND: We first introduced the orthotopic liver transplantation utilizing cavaplasty technique in 1994. This paper describes the surgical technique and assesses the outcome of the cavaplasty OLT. METHODS: The cavaplasty procedure was used in 115 consecutive orthotopic liver transplantations, including six left lateral and two right lobe transplantations, between November 1994 and September 2000. Fifty-three (66.3%) transplantations required femoro-axillary veno-venous bypass in the initial 4 years, whereas only eight (22.9%) needed VB in the subsequent 2 years. Conversion to piggyback or standard technique was not necessary in any patient. RESULTS: Median results are as follows: operative time 4.5 hr, warm ischemia time 25 min, and blood transfused (packed red blood cells) 6 units. These findings did not differ between first transplantation and retransplantation. There were no perioperative deaths related to the cavaplasty technique. No hepatic venous outflow obstruction was observed, including living-related OLTs. No patient required postoperative hemodialysis for acute renal failure. The median intensive care and hospital stays were 2 days and 10 days, respectively. CONCLUSIONS: The cavaplasty technique requires no retrocaval, hepatic vein, or short hepatic vein dissection, and the inferior vena cava can be preserved, which provides advantages for hepatectomy and easy hemostasis, especially during retransplantation. The wide-open triangular caval anastomosis is easy to perform, allowing short implantation time and size matching and avoiding outflow obstruction. The short implantation time reduces the need for veno-venous bypass. Our experience indicates that the cavaplasty technique can be applied to all patients and is justified by minimal technical complications.

Adolescent↗
PubMed2001

Rolipram reduces excitotoxic neuronal damage.

Proinflammatory cytokines are supposed to be involved in the pathophysiology of neuronal damage following excitotoxic lesions. We examined the effect of rolipram, a TNF-alpha-inhibitor, on excitotoxic neuronal damage. Quinolinic acid (240 nmol in 1 microl) was injected stereotactically into the striatum of male Wistar rats. Four groups of QA rats were treated i.p. with solvent, MK-801 (4 mg/kg) or rolipram (0.3 mg/kg) which was started either 6 or 24 h after QA injection and continued with daily applications for 14 days. QA injection induced neuronal damage which affected 93% of the striatal area. MK-801 reduced this damage to 12% of the striatal area. Treatment with rolipram when started at 6 h after QA injection resulted in neuronal damage amounting to 60%; the result after starting at 24 h was not different from solvent (91%). The present results demonstrate that rolipram reduces neuronal damage induced by intrastriatal QA application.

Animals↗
PubMed2001

Neurotransmitter concentrations and binding at dopamine receptors in rats after maternal exposure to 3,4,3',4'-tetrachlorobiphenyl: the role of reduced thyroid hormone concentrations.

Polychlorinated biphenyls (PCBs) are environmental contaminants, which accumulate in the food chain and are transferred to the offspring during prenatal development through the placenta and postnatally via breast milk. It is reported that PCBs exert effects on thyroid hormone levels and brain neurotransmitter levels. Both actions may alter neuronal development. The aim of the present study was to investigate, if PCB-induced effects on concentrations of catecholamines and serotonin can be attributed to PCB-induced reductions in thyroid hormone concentrations. In addition, binding to dopamine D(1) and D(2) receptors was examined. Time-mated Wistar rats were treated prenatally with 1 mg 3,4,3',4'-tetrachlorobiphenyl (PCB 77)/kg bodyweight or the vehicle. A third group serving as the positive control received perinatally 5 mg propylthiouracil (PTU)/l drinking water. There were no overt toxic signs in dams or offspring. Thyroid hormone measurements demonstrated effects in dams and offspring up to postnatal day 40. In particular, total T(4) in serum and in the thyroid were decreased in PCB- and PTU-treated dams and offspring. Only PTU exposed rats exhibited significantly increased concentrations of TSH in the serum and pituitary. Measurement of neurotransmitters revealed changes in the PCB-exposed offspring at PND 40, while PTU-treatment was without effect. Dopamine and DOPAC were increased in the medial prefrontal cortex. In adulthood, there were no PCB-related effects on thyroid hormones and neurotransmitters. Binding studies of dopamine D1 and D2 receptors demonstrated that PCB and PTU had no influence on receptor concentration and affinity. Comparison of PCB 77 exposed offspring to PTU exposed offspring demonstrated differential effects on TSH and neurotransmitter levels, the latter result indicating that not all PCB-induced effects on the nervous system can be ascribed to decreases in thyroid hormone concentrations.

Journal Article↗
PubMed2001

Acclimative changes in root epidermal cell fate in response to Fe and P deficiency: a specific role for auxin?

Root hair formation and the development of transfer cells in the rhizodermis was investigated in various existing auxin-related mutants of Arabidopsis thaliana and in the tomato mutant diageotropica. Wild-type Arabidopsis plants showed increased formation of root hairs when the seedlings were cultivated in Fe- or P-free medium. These extranumerary hairs were located in normal positions and in positions normally occupied by nonhair cells, e.g., over periclinal walls of underlying cortical cells. Defects in auxin transport or reduced auxin sensitivity inhibited the formation of root hairs in response to Fe deficiency completely but did only partly affect initiation and elongation of hairs in P-deficient roots. Application of the ethylene precursor 1-aminocyclopropane-1-carboxylic acid or the auxin analog 2,4-dichlorophenoxyacetic acid did not rescue the phenotype of the auxin-resistant axr2 mutant under control and Fe-deficient conditions, indicating that functional AXR2 product is required for translating the Fe deficiency signal into the formation of extra hairs. The development of extra hairs in axr2 roots under P-replete conditions was not affected by auxin antagonists, suggesting that this process is independent of auxin signaling. In roots of tomato, growth under Fe-deficient conditions induced the formation of transfer cells in the root epidermis. Transfer cell frequency was enhanced by application of 2,4-dichlorophenoxyacetic acid but was not inhibited by the auxin transport inhibitor N-1-naphthylphthalamic acid. In the diageotropica mutant, which displays reduced sensitivity to auxin, transfer cells appeared to develop in both Fe-sufficient and Fe-deficient roots. Similar to the wild type, no reduction in transfer cell frequency was observed after application of the above auxin transport inhibitor. These data suggest that auxin has no primary function in inducing transfer cell development; the formation of transfer cells, however, appears to be affected by the hormonal balance of the plants.

Arabidopsis↗
PubMed2001

[Selective pre- intra- and postoperative bile duct diagnosis--an efficient and low complication regimen within the scope of laparoscopic cholecystectomy. Early and late results of a prospective study].

INTRODUCTION: The discussion of diagnostic pre- and intraoperative procedures of the common bile duct (CBD) for laparoscopic cholecystectomy is still open. METHODS: Results of a prospective study of 4000 laparoscopic cholecystectomies were evaluated, adhering to the concept of selective common bile duct examination. In 1999 an inquiry was performed on 1197 patients an average of 38.7 months postoperatively to judge this concept. RESULTS: Three hundred and nineteen patients (8%) examined preoperatively by ERC revealing a CBD stone in 126 cases. The morbidity of this procedure was 3.1%. In 0.18% a lesion of the common bile duct was documented following laparoscopic cholecysTectomy. A intraoperative cholangiography was performed in 67 patients (1.7%) because of unclear anatomy or to exclude a CBD stone. Perioperatively a CBD stone was found in 0.5% of cases. Additionally, in 0.3% the same problem occurred in the long-term follow-up, so that the risk for unknown CBD stones following the selective diagnostic concept is 0.8%. CONCLUSION: The concept of selective diagnostic procedures of the common bile duct shows a low morbidity with sufficient efficiency in avoiding CBD stones as well as duct lesions. Therefore it is recommended for routine use in laparoscopic cholecystectomy.

Cholangiography↗
PubMed2001

Cinnamic acid is a precursor of benzoic acids in cell cultures of Hypericum androsaemum L. but not in cell cultures of Centaurium erythraea RAFN.

Benzoic acids are precursors of xanthone biosynthesis which has been studied in cell cultures of Hypericum androsaemum (Hypericaceae) and Centaurium erythraea (Gentianaceae). In both cell cultures, methyl jasmonate induces the intracellular accumulation of a new xanthone. Under these inductive conditions, feeding experiments were performed with [U-14C]L-phenylalanine, [7-14C]benzoic acid and [7-14C]3-hydroxybenzoic acid. All three precursors were efficiently incorporated into the elicited xanthone in H. androsaemum, whereas 3-hydroxybenzoic acid was the only precursor to be incorporated into xanthones in C. erythraea. In addition, an appreciable increase in phenylalanine ammonia-lyase activity occurred only in methyl-jasmonate-treated cell cultures of H. androsaemum. Benzoic acids thus appear to be formed by different pathways in the two cell cultures studied. In H. androsaemum, benzoic acid is derived from cinnamic acid by side-chain degradation. In C. erythraea 3-hydroxybenzoic acid appears to originate directly from the shikimate pathway.

Acetates↗
PubMed2001

Fe homeostasis in plant cells: does nicotianamine play multiple roles in the regulation of cytoplasmic Fe concentration?

The cellular and intracellular localization of the non-proteogenic amino acid nicotianamine (NA) in leaves and root elongation zones was immunochemically investigated in pea (Pisum sativum L.) and tomato (Lycopersicon esculentum Mill.) plants grown under various iron regimes and in three mutants defective in the regulation of iron uptake. Strongest immunostaining was observed in the over-accumulating pea mutants brz and dgl, and in iron-loaded wild-type plants. Fe concentration and NA level paralleled staining intensity, indicating that NA synthesis is induced by high iron availability. While label was mainly present in the cytoplasm under normal (10 microM) Fe supply and under Fe deprivation, most of the labeling was present in the vacuole in iron-loaded plants. This pattern resembled the distribution of NA in Fe over-accumulating mutants, indicating the possible importance of vacuolar sequestration in the detoxification of excess Fe. Based on the dependence of the cellular distribution of NA on the iron nutritional status of the plant, a possible role of NA in buffering free Fe in root and leaf cells was inferred. We show here for the first time that the NA concentration is increased in response to iron overload, indicating that, besides other classes of intracellular metal-binding ligands, NA may play an essential role in iron tolerance.

Adaptation, Physiological↗
PubMed2001

Multicenter, comparative study of cycle control, efficacy and tolerability of two low-dose oral contraceptives containing 20 microg ethinylestradiol/100 microg levonorgestrel and 20 microg ethinylestradiol/500 microg norethisterone.

A comparison of cycle control, efficacy and tolerability of two oral contraceptive preparations containing 20 microg ethinylestradiol combined with either 100 microg levonorgestrel (EE/LNG 20/100) or 500 microg norethisterone (EE/NET 20/500) was conducted. These results were compared to a standard reference preparation, containing 30 microg ethinylestradiol combined with 150 microg levonorgestrel (EE/LNG 30/150). Efficacy data from 8,544 treatment cycles were obtained from 767 women. Good cycle control and effective contraception was achieved with the two LNG preparations, however, the cycle control results were less favorable with EE/NET 20/500. The cumulative incidence of women with at least one episode of intermenstrual bleeding from cycles 2 to 7 (primary target variable) was 43.9% for EE/LNG 20/100, 72.7% for EE/NET 20/500, and 15.7% for the standard EE/LNG 30/150. The difference between the 2 20 microg of EE preparations, which favored EE/LNG 20/100, was statistically significant (p = 0.001). The overall spotting rates (cycles 1-13) were 9.3% for EE/LNG 20/100, 21.7% for EE/NET 20/500, and 3.3% for the standard EE/LNG 30/150. Amenorrhea was reported in 7.1% (EE/LNG 20/100), 20.6% (EE/NET 20/500), and 0.9% (standard EE/LNG 30/150), respectively. Intermenstrual bleeding episodes were shorter with EE/LNG 20/100 and EE/LNG 30/150 of the 13 treatment cycles. The study Pearl indices were 0.9 for EE/LNG 20/100, 1.9 for EE/NET 20/500, and 0.0 for EE/LNG 30/150. All three treatments were well tolerated. However, tolerability was somewhat less favorable with EE/NET 20/500. A total of 160 women prematurely discontinued the study for various reasons (EE/LNG 20/100: 7%; EE/NET 20/500: 18%; EE/LNG 30/150: 4%). The overall adverse event incidence rate during the trial was low in all groups. Blood pressure remained largely unaffected. Thirteen serious adverse events were recorded for all treatment groups, all but one were assessed as not related to the treatments. There were no remarkable treatment related differences in mean body weight throughout the study and the laboratory values were largely unaffected in all three treatments groups.

Adolescent↗