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Biomedical subjects

Stefan Scholz

Publications and source records attributed to Stefan Scholz.

At least 19 recordsLinked to original sources
PubMed2007

Continuous SvO2 measurement in infants undergoing congenital heart surgery--first clinical experiences with a new fiberoptic probe.

BACKGROUND: SvO2-guided therapy, using fiberoptic oximetric catheters can help to improve the outcome after complex congenital heart surgery especially in infants undergoing the Stage 1-Norwood-Procedure. So far, fiberoptic catheters have to be placed transthoracically by the surgeon into the vena cava or the pulmonary artery putting the infant at an additional risk of bleeding at the time of catheter removal. METHODS: We used a new percutaneously applicable fiberoptic probe for continuous monitoring of central venous saturation in three infants undergoing modifications of the Stage 1-Norwood-Procedure (reconstruction of the aortic arch), two in combination with a bidirectional cavopulmonary connection (Glenn shunt), the third with reconstruction of the pulmonary arteries (biventricular repair). The approved clinical monitoring system consisted of a small (2 F) fiberoptic probe and a bed-side-monitor. The probe was inserted via the routine central venous access for such a case. RESULTS: Continuous SvO2 measurement is feasible in infants using the CeVOX system in combination with routine central venous access, and the advantages of continuous monitoring are discussed. CONCLUSIONS: We believe that compared with transthoracically inserted oximetric catheter, the presented percutaneous technique avoids additional risks at the time of catheter removal (i.e. bleeding) and has become part of our standard management.

Cardiopulmonary Bypass↗
PubMed2006

Effect of isoflurane on echocardiographic left-ventricular relaxation indices in patients with diastolic dysfunction due to concentric hypertrophy and ischemic heart disease.

OBJECTIVE: The purpose of this study was to investigate whether isoflurane, a known negative lusitropic agent, exacerbates diastolic dysfunction in patients with preexisting impaired relaxation. DESIGN: Prospective, experimental study. SETTING: Single-institution, university hospital. PARTICIPANTS: Twenty-five patients with diastolic dysfunction due to concentric hypertrophy and ischemic heart disease undergoing elective coronary artery bypass graft surgery. INTERVENTIONS: After approval of the local ethics committee and informed consent, patients randomly received sufentanil/midazolam anesthesia plus either 0.5 to 1.0 minimum alveolar concentration of isoflurane (n = 15) or weight-adjusted boli of urapidil (n = 10) during preparation of the internal mammary artery. Changes in hemodynamic parameters and echocardiographic diastolic indices before and after drug administration were compared. Filling pressures during the study were kept constant within normal range. MEASUREMENTS AND MAIN RESULTS: Hemodynamic changes measured by invasive arterial and pulmonary arterial pressures were comparable between isoflurane and urapidil. Both interventions led to a marked reduction in afterload that was accompanied by a significant increase in thermodilution cardiac output and stroke volume. Transesophageal echocardiographic relaxation indices were also comparable between groups. Transmitral and tissue Doppler E waves increased significantly, leading to larger E/A and Em/Am ratios; whereas the deceleration time and the isovolumetric relaxation time decreased significantly. CONCLUSION: Isoflurane did not exacerbate diastolic dysfunction in patients with concentric hypertrophy and ischemic heart disease. In contrast, isoflurane led to a "normalization" of the relaxation pattern that was attributed to a reduction in left-ventricular loading conditions.

Aged↗
PubMed2006

Transplantation in truncus arteriosus combined with interrupted aortic arch.

We present the case of an infant with truncus arteriosus combined with a dysplastic truncal valve not amenable to repair and interrupted aortic arch. Due to the disappointing results of truncal valve replacement we decided to perform cardiac transplantation. The infant survived transplantation and was discharged 4 weeks after surgery.

Aorta, Thoracic↗
PubMed2005

Naringenin-type flavonoids show different estrogenic effects in mammalian and teleost test systems.

The estrogenic activity of several intermediary plant compounds has raised concern about possible risks of unwanted interference with endocrine regulation, but on the other hand there are potential medical benefits, in particular in treatment of menopausal symptoms or cancer. In the present study, we compare the estrogenic effects of phytoestrogens naringenin, 8-prenylnaringenin, 6-(1,1-dimethylallyl)naringenin, and the synthetic 4'-acetyl-7-prenyloxynaringenin. Two mammalian in vitro systems and a fish in vivo system were used to study the estrogenic properties with reference to genistein, 17-beta-estradiol or ethynylestradiol. Strong differences were observed between the mammalian in vitro and the fish in vivo test system. In the medaka sex reversal/vtg gene expression assay no estrogenic effects of the naringenin-type flavonoids were observed, while mammalian in vitro systems showed a similar and graded response to the test compounds.

Animals↗
PubMed2005

Templated ceramic microstructures by using the breath-figure method.

We describe the synthesis of two cyclobutadiene(cyclopentadienyl)cobalt-containing poly(p-phenylene ethynylene)s (PPEs) and their use as precursors for stable ceramic surface coatings. Organometallic PPEs were shaped into hexagonally ordered assemblies by using the breath-figure method. Such breath figures can be washed away with an appropriate solvent. Upon pyrolysis at 500 degrees C under either nitrogen or air, the bubble arrays persist as ceramics and are insoluble in organic solvents or water. The formed pyrolyzed bubble arrays were analyzed by optical and scanning electron microscopy, as well as energy dispersive X-ray microanalysis (EDX). The composition of the ceramic materials is discussed based on EDX and IR data.

Journal Article↗
PubMed2005

Physiologic properties of small intestine submucosa.

BACKGROUND: Porcine small intestine submucosa (SiS) has been introduced as a bioprosthesis in herniorrhaphy. This study evaluates in vivo properties of SiS that would affect clinical use. MATERIALS AND METHODS: Twelve pigs underwent implantation of SiS (perforated and nonperforated) on the peritoneal surface. Gross characteristics were evaluated and random samples harvested for histological study at 2 (n = 6) and 8 (n = 6) weeks. Collagen deposition was determined by polarized microscopy. Neovascularity (percent area blood vessels, %A(bv)) was determined by immunohistochemical staining with a polyclonal CD-31 antibody. RESULTS: Perforated SiS had a higher density of capillary ingrowth compared with nonperforated at both 2 (5.6%A(bv) versus 1.4%A(bv), P < 0.05) and 8 weeks (6.0%A(bv) versus 1.6%A(bv), P < 0.05). Compared with 2 weeks, 8-week SiS had a larger proportion of incorporation (25% versus 83%, P < 0.05) and new collagen deposition (50% versus 94%, P < 0.05). Significant contraction was observed in SiS 8 weeks after implantation (preimplant area 98 cm2 versus post-implant area 50 cm2, P < 0.05). CONCLUSION: SiS incorporated well 8 weeks after implantation, with deposition of new collagen. Perforated SiS demonstrated a more rapid and greater amount of neovascularity. The degree of contraction suggests that larger areas of SiS should be selected for herniorrhaphy than would be necessary if synthetic materials were used.

Absorbable Implants↗
PubMed2005

Analysis of estrogenic effects by quantification of green fluorescent protein in juvenile fish of a transgenic medaka.

TheChgH-GFP strain of the teleost medaka contains a regulatory region of the estrogen-responsive choriogenin H (chgH) gene fussed to the green fluorescent protein (GFP) gene. The strain was developed for the identification of environmental estrogens by noninvasive analysis of GFP fluorescence. In the present study, a quantification method for GFP by image analysis was establishedand applied to the analysis of time- and concentration-dependent GFP fluorescence in juvenile fish. Concentration-response analyses were performed with fish exposed for 14 d to 17beta-estradiol (0.37-367 pM), genistein (0.37-367 nM), or p-nonylphenol (0.367-1,835 nM). By means of image analysis, it was shown that ChgH-GFP was induced at 183.5 pM or greater 17beta-estradiol. Time-course and recovery experiments indicated a strong accumulation of GFP in the liver. Results of reverse transcriptase-polymerase chain reaction analysis of choriogenin H and vitellogenin demonstrated induction of gene expression for the same rangeof concentrations as that for GFP analysis. Neither expression of these genes nor GFP fluorescence was induced by genistein and p-nonylphenol. Although the ChgH-GFP strain failed to detect these weakly estrogenic compounds, the simplicity of the GFP quantification during early life stages of fish offers promising possibilities for further developments of transgenic strains using different target regulatory sequences.

Animals↗
PubMed2004

Germ cell-less expression in medaka (Oryzias latipes).

The gene germ cell-less (gcl) plays an important role in the early differentiation of germ cells in Drosophila. We isolated the gcl homolog of the model teleost medaka (Oryzias latipes) using degenerated primers and an ovary cDNA bank. The predicted amino acid sequence of medaka gcl showed 92, 68 and 31% overall identity to mouse, human and Drosophila gcl respectively. RT-PCR revealed stronger expression in the ovary and weaker expression in testis, brain, heart, liver and muscle tissue. Expression in early embryos indicates the presence of maternal mRNA. By in situ hybridisation (ISH), gcl could not be detected in embryos. In contrast to vasa, ISH revealed expression of gcl in the ovary but not in the testis. Mol. Reprod. Dev. 67: 15-18, 2004.

Amino Acid Sequence↗
PubMed2004

Induction of vitellogenin in vivo and in vitro in the model teleost medaka (Oryzias latipes): comparison of gene expression and protein levels.

Quantification of the egg yolk precursor vitellogenin (VTG) in fish has become a standard technique to detect estrogenic effects of known chemicals and environmental samples. In the present study, we have analysed VTG induction by estradiol, ethynylestradiol and genistein exposure in the model teleost medaka (Oryzias latipes) and demonstrate that the medaka is a suitable model system to analyse estrogenic effects. By comparing VTG gene expression and protein levels we show that in principal both techniques can be used to study VTG induction in vivo (juvenile and adult males) and in vitro (primary cultures of male liver cells). If a short term in vivo or in vitro exposure is performed, detection of mRNA might be sufficient. For long term studies with the need to detect weak estrogenic chemicals and a precise quantification, immuno-chemical detection may be favoured.

Animals↗
PubMed2003

Hormonal induction and stability of monosex populations in the medaka (Oryzias latipes): expression of sex-specific marker genes.

The model teleost medaka (Oryzias latipes, d-rR.YHNI strain) was used to produce offspring of a defined sex (monosex populations) by crossing experimentally produced YY and XX males to normal females. These monosex populations had the predicted chromosomal constitution as shown by a sex chromosome-specific DNA sequence. However, in XX populations the spontaneous development of males without previous exposure to androgens was observed. Differences in the percentage of male offspring from individual XX breeding pairs indicate a possible variation of unknown genetic factors to be responsible for the development of XX males. The expression of two gonadal genes that are involved in sex differentiation, Dmrt1b(Y) and Fig1a (factor in the germ line alpha), was analyzed in monosex populations. Dmrt1b(Y) expression correlated strictly with the genotype but not the sexual phenotype. When XY juvenile fish were exposed to 17 alpha-ethynylestradiol at concentrations that induce sex reversal, Dmrt1b(Y) expression was not repressed. However, Dmrt1b(Y) was expressed in XY or YY gonads regardless of the sex and could not be detected in XX individuals. In contrast, the expression of Fig1a correlated with the phenotypic sex: Fig1a was expressed in male juvenile fish exposed to 17 alpha-ethynylestradiol and repressed in fish exposed to 17 alpha-methyltestosterone. The Dmrt1b(Y) expression appears to reflect an early and important event in sex determination and lends support to the suggested key regulatory role of the Dmrt1b(Y) gene in sex determination. This process is apparently hormone insensitive, and the expression of further downstream acting genes can be regulated (directly or indirectly) by sex steroids.

Actins↗
PubMed2003

A combined stage 1 and 2 repair for hypoplastic left heart syndrome: anaesthetic considerations.

Therapy of hypoplastic left heart syndrome (HLHS) consists of the staged Norwood procedure or cardiac transplantation. Stenting the ductus arteriosus and subsequent banding of the pulmonary arteries allows the combination of neoaortic reconstruction with the establishment of a bidirectional cavopulmonary connection (combined stage 1 and 2 procedure) in a later session. We report the anaesthetic management in eight infants ranging from 107 to 195 days undergoing a combined stage 1 and 2 procedure. Nonselective pulmonary vasodilators and nitric oxide were needed in all cases to improve oxygen saturation in the postbypass period. Phosphodiesterase inhibitors and epinephrine were required in all patients for inotropic support during and after weaning off cardiopulmonary bypass. The procedure was successful in seven patients. One patient died intraoperatively because of right heart failure. The physiological changes of this new surgical strategy for palliation of HLHS offers a challenge for the anaesthetist primarily in the early postbypass period.

Anesthetics, Intravenous↗
PubMed2002

The low-temperature phase of di-tert-butylsilanediol.

The crystal structure of di-tert-butylsilanediol, C(8)H(20)O(2)Si, has a reversible phase transition at 211 (2) K. The orthorhombic high-temperature structure has space group Ibam, with Z' = 1/2, and shows a disordered hydrogen-bonding system. The low-temperature structure, determined at 143 (2) K, has a twinned monoclinic cell, with space group C2/c and Z' = 2, and shows an ordered hydrogen-bonding system.

Journal Article↗
PubMed2002

Ligamentous rupture of the ACL associated with dislocated fracture of the proximal tibial physis in a 12-year-old boy.

BACKGROUND: Dislocated fracture of the proximal physeal plate of the tibia with or without metaphyseal fragment is rare in children. This unusual fracture classically excludes rupture of the anterior cruciate ligament due to the ligament's stability. A combination of both injuries has not been previously published in the literature. CASE PRESENTATION: The authors report the case of a 12-year-old boy who presented with a dislocated fracture (Salter-Harris II) of the proximal tibia combined with ligamentous rupture of the anterior cruciate ligament after a sporting accident.

Journal Article↗
PubMed2002

Computerize anesthesia record keeping in thoracic surgery--suitability of electronic anesthesia records in evaluating predictors for hypoxemia during one-lung ventilation.

OBJECTIVE: The aim of this retrospective study was to assess the suitability of routine data gathered with a computerized anesthesia record keeping system in investigating predictors for intraoperative hypoxemia (SpO2 < 90%) during one-lung ventilation (OLV) in pulmonary surgery. METHODS: Over a four-year period data of 705 patients undergoing thoracic surgery (pneumonectomy: 78; lobectomy: 292; minor pulmonary resections: 335) were recorded online using an automated anesthesia record-keeping system. Twenty-six patient-related, surgery-related and anesthesia-related variables were studied for a possible association with the occurrence of intraoperative hypoxemia during OLV. Data were analyzed using univariate and multivariate (logistic regression) analysis (p < 0.05). The model's discriminative power on hypoxemia was checked with a receiver operating characteristic (ROC) curve. Calibration was tested using the Hosmer-Lemeshow goodness-of-fit test. RESULTS: An intraoperative incidence of hypoxemia during OLV was found in 67 patients (9.5%). Using logistic regression with a forward stepwise algorithm, body-mass-index (BMI, p = 0.018) and preoperative existing pneumonia (p = 0.043) could be detected as independent predictors having an influence on the incidence of hypoxemia during OLV. An acceptable goodness-of-fit could be observed using cross validation for the model (C = 8.21, p = 0.370, degrees of freedom, df 8; H = 3.21, p = 0.350, df 3), the discriminative power was poor with an area under the ROC curve of 0.58 [0.51-0.66]. CONCLUSIONS: In contrast to conventional performed retrospective studies, data were directly available for analyses without any manual intervention. Due to incomplete information and imprecise definitions of parameters, data of computerized anesthesia records collected in routine are helpful but not satisfactory in evaluating risk factors for hypoxemia during OLV.

Adult↗
PubMed2002

Laparoscopic adhesiolysis and placement of Seprafilm: a new technique and novel approach to patients with intractable abdominal pain.

Patients who suffer from chronic abdominal pain as a result of postoperative adhesion formation are challenging to treat. Many surgeons argue that operative treatment of these patients exacerbates symptoms because of the continued adhesion formation following each procedure. Seprafilm (Genzyme, Tucker, GA, USA), a bioresorbable membrane of sodium hyaluronate and carboxymethylcellulose, and laparoscopic surgery have both been shown to significantly decrease postoperative adhesion formation. Although the utility of laparoscopy is controversial in the treatment of these patients, the combination of laparoscopy and Seprafilm can provide excellent relief in this difficult patient population. We report a new technique, laparoscopic adhesiolysis and Seprafilm placement, for patients with intractable abdominal pain secondary to adhesions.

Abdominal Pain↗