Biomedical subjects

Andreas Schneider

Publications and source records attributed to Andreas Schneider.

9 recordsLinked to original sources

PubMed2006

Ureterosciatic hernia with compression of the sciatic nerve.

Ureterosciatic herniation is a rare cause of ureteral obstruction. Sciatic hernia is a well-defined anatomic defect that is the result of atrophy or abnormal development of piriform muscle. Patients with sciaitic hernias commonly present with symptoms of flank, abdominal, pelvic, lower back or thigh pain. The hernia sack can contain small bowel, ureter, ovary, colon or bladder. Ureterosciatic hernia causing ureteral obstruction should be surgical repaired.

Female↗

PubMed2006

The mu-opioid receptor gene polymorphism 118A>G depletes alfentanil-induced analgesia and protects against respiratory depression in homozygous carriers.

AIM: To investigate whether OPRM1 118A>G polymorphism affects analgesic and respiratory depressive effects of alfentanil and assess its role for the therapeutic range of alfentanil. METHODS: In an open-label, single-occasion design, 10 non-carriers, four heterozygous and six homozygous carriers of the variant OPRM1 118G allele received a computerized infusion of alfentanil to achieve target effect-site concentrations of 0, 33.33, 66.67 and 100 ng/ml. At each concentration level, analgesia was assessed by means of electrically and chemically induced pain, and respiratory depression was quantified by hypercapnic challenge and breathing frequency. RESULTS: The relationship between the percent change of tolerance to electrical stimuli and measured alfentanil concentrations, described by power models, was flatter in carriers of the 118G variant allele than in non-carriers, indicating decreased opioid analgesia (P<0.05). For chemically induced pain, a flatter analgesia versus concentration relationship was found only for homozygous carriers of the 118G allele (P<0.05). The relationship between the percent changes in respiratory parameters was significantly flatter (P<0.01) only in homozygous carriers as compared to heterozygous carriers and non-carriers of the 118G allele. Higher alfentanil concentrations were needed in homozygous carriers as compared to wild-type subjects (2-4 times) to produce the same degree of analgesia, whereas 10-12 times higher alfentanil concentrations were needed to produce the same degree of respiratory depression. CONCLUSION: OPRM1 118A>G polymorphism affects both analgesic and respiratory depressive effects of alfentanil. However, while the analgesic effects are already partly decreased in heterozygous carriers, depending on the pain model, the respiratory depressive effects are decreased in homozygous carriers of the variant 118G allele. The therapeutic range of alfentanil was only broadened in homozygous carriers.

Adult↗

PubMed2006

Endometriosis of the urinary tract in women of reproductive age.

AIM: We present our experience with diagnosing and treating 22 cases of urinary tract endometriosis in women of reproductive age. PATIENTS AND METHODS: From January 2001 to January 2003, 22 women of reproductive age (mean age 34.8 years) were diagnosed suffering from endometriosis of the urinary tract. We used the Endoscopic Endometriosis Classification (EEC) for assessing the stage of endometriosis. RESULTS: Endometriosis was present in the bladder, the lower third of the ureter, and in a postnephrectomy ureteral stump in 15 (68.1%), six (27.2%) and one (4.5%) cases, respectively. The EEC classification revealed stages I, II, III and IV in four (18.1%), one (4.5%), one (4.5%), and 16 (72.7%) patients, respectively. Urinary symptoms were present in 14 (63.6%) patients. For the treatment of bladder endometriosis, 10 patients underwent partial cystectomy, while the remaining five patients were treated with transurethral resection. In four patients ureterolysis was performed, by laparoscopy in two cases and by open surgery in the other two cases. Ureterectomy and re-implantation with bladder psoas hitching took place in six patients. In the case of endometriosis of the ureteral stump, open surgical excision took place. During the mean follow-up period of 20 months (range 16-40) no long-term complication or relapse was diagnosed. CONCLUSIONS: Bladder and ureteral endometriosis should be considered in women of reproductive age with non-specific urinary tract or abdominal symptoms, and surgical treatment is recommended.

Adult↗

PubMed2006

The presence of gestational diabetes is associated with increased detection of anti-HLA-class II antibodies in the maternal circulation.

PROBLEM: Gestational diabetes (GD) may be associated with temporarily reduced immune tolerance toward alloantigens for the time of pregnancy. The aim of this study was to assess anti-HLA-class I and -II antibodies as markers for an aberrant immunostimulation in women with GD. METHOD OF STUDY: The percentage of anti-HLA-class I and -II antibodies was estimated in women with GD, normal term delivery and fetal distress, which was confirmed by demonstrating low cord blood pH for this patient group. These antibodies may cross the placental barrier and cause interleukin-6 (IL-6) release from fetal monocytes by cross-linking monocytes with antibody-loaded cells. Therefore we estimated the percentage of IL-6-positive monocytes in the fetal circulation of these three patient groups. RESULTS: We found a significantly increased percentage of anti-HLA-class II in the circulation of women with GD. In comparison with women with normal term delivery, a significantly increased percentage of IL-6-positive monocytes was detected for women with GD and for women with fetal distress. Significantly decreased cord blood pH were detected for neonates born in the presence of fetal distress but not for neonates born in the presence of GD. CONCLUSIONS: Our results suggest that GD is associated with an increased humoral immune response against HLA-class II antigens.

Diabetes, Gestational↗

PubMed2005

The 5-hydroxytryptamine 4 receptor agonist mosapride does not antagonize morphine-induced respiratory depression.

BACKGROUND: On the basis of experiments in rats, serotonin 4 receptor (5-hydroxytryptamine 4 [5-HT4]) agonists have been proposed as a novel therapeutic strategy for the selective treatment of respiratory depression caused by opioids while leaving analgesic effects unaffected. The effects in rats have been seen with the 5-hydroxytryptamine 4a (5-HT4a) agonist BIMU8, which is currently not available for use in humans. METHODS: In a proof-of-applicability study, the clinically recommended dose of 5 mg mosapride, currently the only 5-HT4 agonist available for clinical use, was given in a placebo-controlled manner 3 times daily for 5 days to 12 healthy men and women. During the actual experiments, a further 15 mg mosapride was administered. After baseline measurements of respiratory depression, by use of a carbon dioxide rebreathing method, and of pain, by use of electrical and chemical pain stimuli, 30 mg morphine per 70 kg body weight was administered intravenously within 2 hours. After assessment of respiratory depression and pain, 2 mg naloxone was intravenously administered within 20 minutes, followed by a third assessment of respiratory depression and pain. In ancillary experiments 10 rats received 100 mg/kg mosapride orally or placebo 50 minutes before intraperitoneal injection of 10 mg/kg morphine, followed 20 minutes later by injection of naloxone, and the respiratory frequency was monitored. RESULTS: With placebo coadministration, the slope of the relationship between expiratory volume and CO2 concentration in the inspired air was significantly reduced, from 1.11 +/- 0.46 L/mm Hg CO2 at baseline to 0.39 +/- 0.25 L/mm Hg CO2 at the end of the morphine infusion (P < .001). Coadministration of mosapride had no effect on respiratory depression induced by morphine (slope of 0.39 +/- 0.19 L/mm Hg CO2, P > .7). In contrast, naloxone significantly reversed the slope to 0.78 +/- 0.36 L/mm Hg CO2 (P = .001). Morphine produced significant effects on electrical and chemical pain stimuli, which were partially reversed by naloxone, but mosapride did not affect the analgesic effects of morphine. In rats mosapride similarly failed to prevent a slowing of the breathing frequency after morphine administration but naloxone reversed the respiratory depression. CONCLUSION: Our results show that, with mosapride, opioid-induced respiratory depression cannot be prevented, and because other 5-HT4 agonists are not currently available for clinical use, a cure for opioid-induced respiratory depression as promised by the previous successful experiments in laboratory animals is not yet available in clinical practice.

Adult↗

PubMed2004

Osteoblast-like cell response to bioactive composites-surface-topography and composition effects.

Two bioactive composites, containing 40 vol % filler in high-density polyethylene (HDPE), were investigated to examine the effects of different filler compositions and different surface patterning. The first composite, known as HAPEX, consists of hydroxyapatite within HDPE, and the second composite, known as AWPEX, consists of glass-ceramic apatite-wollastonite in HDPE. Surface topography effects at 5-50 and 100-150 microm were explored, with cell morphology analyzed with the use of scanning electron microscopy and confocal laser scanning microscopy (CLSM). Biochemical assays of adenosine triphosphate and alkaline phosphatase were used to analyze osteoblast-like cell proliferation and differentiation. For both composites, cell alignment was seen along grooves, pillars, and wells, with preferential cell attachment to ceramic particles within the polymer matrices. HAPEX showed significantly increased cell proliferation over AWPEX (P < 0.005). However, greater cell differentiation occurred for AWPEX over HAPEX (P < 0.005). Polishing significantly increased osteoblast-like cell response over as-cut samples, but surface-topography changes above 50 microm had no consistent effect. Smaller-scale features also showed no significant trend in terms of cell proliferation, but did show significant differences in cell differentiation (P < 0.05). CLSM imaging of actin and vinculin localization within cells showed the greatest change in comparison to polished surface controls for cells cultured on samples with surface features below 50 microm. The fact that similar observations were made for both HAPEX and AWPEX indicated that, for these experiments, the effects of surface topography more strongly influenced cell response than chemical composition.

Adenosine Triphosphate↗

PubMed2003

Noninvasive measurement of torque development in the rat foot: measurement setup and results from stimulation of the sciatic nerve with polyimide-based cuff electrodes.

In neural rehabilitation, selective activation of muscles after electrical stimulation is mandatory for control of paralyzed limbs. For an evaluation of electrode selectivity, a setup to noninvasively measure the force development after electrical stimulation in the rat foot was developed. The setup was designed in accordance to the anatomical features of the rat model to test the isometric torque development at given ankle positions in an intact leg. In this paper, the setup design and development is presented and discussed. In a first study, the selectivity of small nerve cuffs with 12 electrodes implanted around the rat sciatic nerve was investigated. Special attention was drawn to the performance of the torque measurement setup in comparison to electrophysiological data obtained from compound muscle action potential recordings. Using one cuff around the nerve, electrical stimulation on different electrode tripoles led to plantarflexion and dorsiflexion of the foot without an a priori alignment of the cuff.

Animals↗

PubMedDate not supplied

Reliability and validity of the work and social adjustment scale in phobic disorders.

The Work and Social Adjustment Scale (WSAS) is a simple widely used 5-item measure of disability whose psychometric properties need more analysis in phobic disorders. The reliability, factor structure, validity, and sensitivity to change of the WSAS were studied in 205 phobic patients (73 agoraphobia, 62 social phobia, and 70 specific phobia) who participated in various open and randomized trials of self-exposure therapy. Internal consistency of the WSAS was excellent in all phobics pooled and in agoraphobics and social phobics separately. Principal components analysis extracted a single general factor of disability. Specific phobics gave less consistent ratings across WSAS items, suggesting that some items were less relevant to their problem. Internal consistency was marginally higher for self-ratings than clinician ratings of the WSAS. Self-ratings and clinician ratings correlated highly though patients tended to rate themselves as more disabled than clinicians did. WSAS total scores reflected differences in phobic severity and improvement with treatment. The WSAS is a valid, reliable, and change-sensitive measure of work/social and other adjustment in phobic disorders, especially in agoraphobia and social phobia.

Adult↗

PubMedDate not supplied

Implantable flexible electrodes for functional electrical stimulation.

A manufacturing technology has been developed to fabricate microelectrode systems with reportedly high numbers of electrodes and high reproducibility. The approach leads to flexible microimplants without the need for heavy and large titanium or ceramic housings.

Coated Materials, Biocompatible↗